diff --git a/doc/api/url.md b/doc/api/url.md
index 088ea95d23f22b..857611a0f29e46 100644
--- a/doc/api/url.md
+++ b/doc/api/url.md
@@ -1049,23 +1049,25 @@ located within the structure of the URL. The WHATWG URL Standard uses a more
 selective and fine grained approach to selecting encoded characters than that
 used by the older [`url.parse()`][] and [`url.format()`][] methods.
 
-The WHATWG algorithm defines three "encoding sets" that describe ranges of
-characters that must be percent-encoded:
+The WHATWG algorithm defines three "percent-encode sets" that describe ranges
+of characters that must be percent-encoded:
 
-* The *simple encode set* includes code points in range U+0000 to U+001F
-  (inclusive) and all code points greater than U+007E.
+* The *C0 control percent-encode set* includes code points in range U+0000 to
+  U+001F (inclusive) and all code points greater than U+007E.
 
-* The *default encode set* includes the *simple encode set* and code points
-  U+0020, U+0022, U+0023, U+003C, U+003E, U+003F, U+0060, U+007B, and U+007D.
+* The *path percent-encode set* includes the *C0 control percent-encode set*
+  and code points U+0020, U+0022, U+0023, U+003C, U+003E, U+003F, U+0060,
+  U+007B, and U+007D.
 
-* The *userinfo encode set* includes the *default encode set* and code points
-  U+002F, U+003A, U+003B, U+003D, U+0040, U+005B, U+005C, U+005D, U+005E, and
-  U+007C.
+* The *userinfo encode set* includes the *path percent-encode set* and code
+  points U+002F, U+003A, U+003B, U+003D, U+0040, U+005B, U+005C, U+005D,
+  U+005E, and U+007C.
 
-The *simple encode set* is used primary for URL fragments and certain specific
-conditions for the path. The *userinfo encode set* is used specifically for
-username and passwords encoded within the URL. The *default encode set* is used
-for all other cases.
+The *userinfo percent-encode set* is used exclusively for username and
+passwords encoded within the URL. The *path percent-encode set* is used for the
+path of most URLs. The *C0 control percent-encode set* is used for all
+other cases, including URL fragments in particular, but also host and path
+under certain specific conditions.
 
 When non-ASCII characters appear within a hostname, the hostname is encoded
 using the [Punycode][] algorithm. Note, however, that a hostname *may* contain
diff --git a/lib/internal/url.js b/lib/internal/url.js
index 771a916d704bac..9929c006d53e49 100644
--- a/lib/internal/url.js
+++ b/lib/internal/url.js
@@ -8,6 +8,8 @@ const {
 const binding = process.binding('url');
 const context = Symbol('context');
 const cannotBeBase = Symbol('cannot-be-base');
+const cannotHaveUsernamePasswordPort =
+    Symbol('cannot-have-username-password-port');
 const special = Symbol('special');
 const searchParams = Symbol('query');
 const querystring = require('querystring');
@@ -42,7 +44,7 @@ const kOpaqueOrigin = 'null';
 // - https://html.spec.whatwg.org/multipage/browsers.html#ascii-serialisation-of-an-origin
 function serializeTupleOrigin(scheme, host, port, unicode = true) {
   const unicodeHost = unicode ? domainToUnicode(host) : host;
-  return `${scheme}//${unicodeHost}${port == null ? '' : `:${port}`}`;
+  return `${scheme}//${unicodeHost}${port === null ? '' : `:${port}`}`;
 }
 
 // This class provides the internal state of a URL object. An instance of this
@@ -54,14 +56,14 @@ function serializeTupleOrigin(scheme, host, port, unicode = true) {
 class URLContext {
   constructor() {
     this.flags = 0;
-    this.scheme = undefined;
-    this.username = undefined;
-    this.password = undefined;
-    this.host = undefined;
-    this.port = undefined;
+    this.scheme = ':';
+    this.username = '';
+    this.password = '';
+    this.host = null;
+    this.port = null;
     this.path = [];
-    this.query = undefined;
-    this.fragment = undefined;
+    this.query = null;
+    this.fragment = null;
   }
 }
 
@@ -70,10 +72,10 @@ function onParseComplete(flags, protocol, username, password,
   var ctx = this[context];
   ctx.flags = flags;
   ctx.scheme = protocol;
-  ctx.username = username;
-  ctx.password = password;
+  ctx.username = (flags & binding.URL_FLAGS_HAS_USERNAME) !== 0 ? username : '';
+  ctx.password = (flags & binding.URL_FLAGS_HAS_PASSWORD) !== 0 ? password : '';
   ctx.port = port;
-  ctx.path = path;
+  ctx.path = (flags & binding.URL_FLAGS_HAS_PATH) !== 0 ? path : [];
   ctx.query = query;
   ctx.fragment = fragment;
   ctx.host = host;
@@ -101,52 +103,37 @@ function parse(url, input, base) {
 
 function onParseProtocolComplete(flags, protocol, username, password,
                                  host, port, path, query, fragment) {
-  const newIsSpecial = (flags & binding.URL_FLAGS_SPECIAL) !== 0;
-  const s = this[special];
   const ctx = this[context];
-  if ((s && !newIsSpecial) || (!s && newIsSpecial)) {
-    return;
-  }
-  if (protocol === 'file:' &&
-    (ctx.username || ctx.password || ctx.port !== undefined)) {
-    return;
-  }
-  if (ctx.scheme === 'file:' && !ctx.host) {
-    return;
-  }
-  if (newIsSpecial) {
+  if ((flags & binding.URL_FLAGS_SPECIAL) !== 0) {
     ctx.flags |= binding.URL_FLAGS_SPECIAL;
   } else {
     ctx.flags &= ~binding.URL_FLAGS_SPECIAL;
   }
-  if (protocol) {
-    ctx.scheme = protocol;
-    ctx.flags |= binding.URL_FLAGS_HAS_SCHEME;
-  } else {
-    ctx.flags &= ~binding.URL_FLAGS_HAS_SCHEME;
-  }
+  ctx.scheme = protocol;
 }
 
 function onParseHostComplete(flags, protocol, username, password,
                              host, port, path, query, fragment) {
   const ctx = this[context];
-  if (host) {
+  if ((flags & binding.URL_FLAGS_HAS_HOST) !== 0) {
     ctx.host = host;
     ctx.flags |= binding.URL_FLAGS_HAS_HOST;
   } else {
+    ctx.host = null;
     ctx.flags &= ~binding.URL_FLAGS_HAS_HOST;
   }
-  if (port !== undefined)
+  if (port !== null)
     ctx.port = port;
 }
 
 function onParseHostnameComplete(flags, protocol, username, password,
                                  host, port, path, query, fragment) {
   const ctx = this[context];
-  if (host) {
+  if ((flags & binding.URL_FLAGS_HAS_HOST) !== 0) {
     ctx.host = host;
     ctx.flags |= binding.URL_FLAGS_HAS_HOST;
   } else {
+    ctx.host = null;
     ctx.flags &= ~binding.URL_FLAGS_HAS_HOST;
   }
 }
@@ -159,29 +146,29 @@ function onParsePortComplete(flags, protocol, username, password,
 function onParsePathComplete(flags, protocol, username, password,
                              host, port, path, query, fragment) {
   const ctx = this[context];
-  if (path) {
+  if ((flags & binding.URL_FLAGS_HAS_PATH) !== 0) {
     ctx.path = path;
     ctx.flags |= binding.URL_FLAGS_HAS_PATH;
   } else {
+    ctx.path = [];
     ctx.flags &= ~binding.URL_FLAGS_HAS_PATH;
   }
+
+  // The C++ binding may set host to empty string.
+  if ((flags & binding.URL_FLAGS_HAS_HOST) !== 0) {
+    ctx.host = host;
+    ctx.flags |= binding.URL_FLAGS_HAS_HOST;
+  }
 }
 
 function onParseSearchComplete(flags, protocol, username, password,
                                host, port, path, query, fragment) {
-  const ctx = this[context];
-  ctx.query = query;
+  this[context].query = query;
 }
 
 function onParseHashComplete(flags, protocol, username, password,
                              host, port, path, query, fragment) {
-  const ctx = this[context];
-  if (fragment) {
-    ctx.fragment = fragment;
-    ctx.flags |= binding.URL_FLAGS_HAS_FRAGMENT;
-  } else {
-    ctx.flags &= ~binding.URL_FLAGS_HAS_FRAGMENT;
-  }
+  this[context].fragment = fragment;
 }
 
 function getEligibleConstructor(obj) {
@@ -214,6 +201,14 @@ class URL {
     return (this[context].flags & binding.URL_FLAGS_CANNOT_BE_BASE) !== 0;
   }
 
+  // https://url.spec.whatwg.org/#cannot-have-a-username-password-port
+  get [cannotHaveUsernamePasswordPort]() {
+    const { host, scheme } = this[context];
+    return ((host == null || host === '') ||
+            this[cannotBeBase] ||
+            scheme === 'file:');
+  }
+
   [util.inspect.custom](depth, opts) {
     if (this == null ||
         Object.getPrototypeOf(this[context]) !== URLContext.prototype) {
@@ -235,7 +230,7 @@ class URL {
     obj.origin = this.origin;
     obj.protocol = this.protocol;
     obj.username = this.username;
-    obj.password = (opts.showHidden || ctx.password == null) ?
+    obj.password = (opts.showHidden || ctx.password === '') ?
                      this.password : '--------';
     obj.host = this.host;
     obj.hostname = this.hostname;
@@ -270,14 +265,11 @@ Object.defineProperties(URL.prototype, {
         auth: true
       }, options);
       const ctx = this[context];
-      var ret;
-      if (this.protocol)
-        ret = this.protocol;
-      if (ctx.host !== undefined) {
+      var ret = ctx.scheme;
+      if (ctx.host !== null) {
         ret += '//';
-        const has_username = typeof ctx.username === 'string';
-        const has_password = typeof ctx.password === 'string' &&
-                             ctx.password !== '';
+        const has_username = ctx.username !== '';
+        const has_password = ctx.password !== '';
         if (options.auth && (has_username || has_password)) {
           if (has_username)
             ret += ctx.username;
@@ -292,9 +284,9 @@ Object.defineProperties(URL.prototype, {
       }
       if (this.pathname)
         ret += this.pathname;
-      if (options.search && typeof ctx.query === 'string')
+      if (options.search && ctx.query !== null)
         ret += `?${ctx.query}`;
-      if (options.fragment && typeof ctx.fragment === 'string')
+      if (options.fragment && ctx.fragment !== null)
         ret += `#${ctx.fragment}`;
       return ret;
     }
@@ -363,7 +355,12 @@ Object.defineProperties(URL.prototype, {
       scheme = `${scheme}`;
       if (scheme.length === 0)
         return;
-      binding.parse(scheme, binding.kSchemeStart, null, this[context],
+      const ctx = this[context];
+      if (ctx.scheme === 'file:' &&
+          (ctx.host === '' || ctx.host === null)) {
+        return;
+      }
+      binding.parse(scheme, binding.kSchemeStart, null, ctx,
                     onParseProtocolComplete.bind(this));
     }
   },
@@ -371,16 +368,16 @@ Object.defineProperties(URL.prototype, {
     enumerable: true,
     configurable: true,
     get() {
-      return this[context].username || '';
+      return this[context].username;
     },
     set(username) {
       // toUSVString is not needed.
       username = `${username}`;
-      if (!this.hostname)
+      if (this[cannotHaveUsernamePasswordPort])
         return;
       const ctx = this[context];
-      if (!username) {
-        ctx.username = null;
+      if (username === '') {
+        ctx.username = '';
         ctx.flags &= ~binding.URL_FLAGS_HAS_USERNAME;
         return;
       }
@@ -392,16 +389,16 @@ Object.defineProperties(URL.prototype, {
     enumerable: true,
     configurable: true,
     get() {
-      return this[context].password || '';
+      return this[context].password;
     },
     set(password) {
       // toUSVString is not needed.
       password = `${password}`;
-      if (!this.hostname)
+      if (this[cannotHaveUsernamePasswordPort])
         return;
       const ctx = this[context];
-      if (!password) {
-        ctx.password = null;
+      if (password === '') {
+        ctx.password = '';
         ctx.flags &= ~binding.URL_FLAGS_HAS_PASSWORD;
         return;
       }
@@ -415,7 +412,7 @@ Object.defineProperties(URL.prototype, {
     get() {
       const ctx = this[context];
       var ret = ctx.host || '';
-      if (ctx.port !== undefined)
+      if (ctx.port !== null)
         ret += `:${ctx.port}`;
       return ret;
     },
@@ -423,15 +420,8 @@ Object.defineProperties(URL.prototype, {
       const ctx = this[context];
       // toUSVString is not needed.
       host = `${host}`;
-      if (this[cannotBeBase] ||
-          (this[special] && host.length === 0)) {
-        // Cannot set the host if cannot-be-base is set or
-        // scheme is special and host length is zero
-        return;
-      }
-      if (!host) {
-        ctx.host = null;
-        ctx.flags &= ~binding.URL_FLAGS_HAS_HOST;
+      if (this[cannotBeBase]) {
+        // Cannot set the host if cannot-be-base is set
         return;
       }
       binding.parse(host, binding.kHost, null, ctx,
@@ -448,15 +438,8 @@ Object.defineProperties(URL.prototype, {
       const ctx = this[context];
       // toUSVString is not needed.
       host = `${host}`;
-      if (this[cannotBeBase] ||
-          (this[special] && host.length === 0)) {
-        // Cannot set the host if cannot-be-base is set or
-        // scheme is special and host length is zero
-        return;
-      }
-      if (!host) {
-        ctx.host = null;
-        ctx.flags &= ~binding.URL_FLAGS_HAS_HOST;
+      if (this[cannotBeBase]) {
+        // Cannot set the host if cannot-be-base is set
         return;
       }
       binding.parse(host, binding.kHostname, null, ctx,
@@ -468,17 +451,16 @@ Object.defineProperties(URL.prototype, {
     configurable: true,
     get() {
       const port = this[context].port;
-      return port === undefined ? '' : String(port);
+      return port === null ? '' : String(port);
     },
     set(port) {
       // toUSVString is not needed.
       port = `${port}`;
-      const ctx = this[context];
-      if (!ctx.host || this[cannotBeBase] ||
-          this.protocol === 'file:')
+      if (this[cannotHaveUsernamePasswordPort])
         return;
+      const ctx = this[context];
       if (port === '') {
-        ctx.port = undefined;
+        ctx.port = null;
         return;
       }
       binding.parse(port, binding.kPort, null, ctx,
@@ -492,7 +474,9 @@ Object.defineProperties(URL.prototype, {
       const ctx = this[context];
       if (this[cannotBeBase])
         return ctx.path[0];
-      return ctx.path !== undefined ? `/${ctx.path.join('/')}` : '';
+      if (ctx.path.length === 0)
+        return '';
+      return `/${ctx.path.join('/')}`;
     },
     set(path) {
       // toUSVString is not needed.
@@ -507,13 +491,15 @@ Object.defineProperties(URL.prototype, {
     enumerable: true,
     configurable: true,
     get() {
-      const ctx = this[context];
-      return !ctx.query ? '' : `?${ctx.query}`;
+      const { query } = this[context];
+      if (query === null || query === '')
+        return '';
+      return `?${query}`;
     },
     set(search) {
       const ctx = this[context];
       search = toUSVString(search);
-      if (!search) {
+      if (search === '') {
         ctx.query = null;
         ctx.flags &= ~binding.URL_FLAGS_HAS_QUERY;
       } else {
@@ -539,8 +525,10 @@ Object.defineProperties(URL.prototype, {
     enumerable: true,
     configurable: true,
     get() {
-      const ctx = this[context];
-      return !ctx.fragment ? '' : `#${ctx.fragment}`;
+      const { fragment } = this[context];
+      if (fragment === null || fragment === '')
+        return '';
+      return `#${fragment}`;
     },
     set(hash) {
       const ctx = this[context];
@@ -553,6 +541,7 @@ Object.defineProperties(URL.prototype, {
       }
       if (hash[0] === '#') hash = hash.slice(1);
       ctx.fragment = '';
+      ctx.flags |= binding.URL_FLAGS_HAS_FRAGMENT;
       binding.parse(hash, binding.kFragment, null, ctx,
                     onParseHashComplete.bind(this));
     }
@@ -1384,10 +1373,10 @@ function constructUrl(flags, protocol, username, password,
   var ctx = new URLContext();
   ctx.flags = flags;
   ctx.scheme = protocol;
-  ctx.username = username;
-  ctx.password = password;
+  ctx.username = (flags & binding.URL_FLAGS_HAS_USERNAME) !== 0 ? username : '';
+  ctx.password = (flags & binding.URL_FLAGS_HAS_PASSWORD) !== 0 ? password : '';
   ctx.port = port;
-  ctx.path = path;
+  ctx.path = (flags & binding.URL_FLAGS_HAS_PATH) !== 0 ? path : [];
   ctx.query = query;
   ctx.fragment = fragment;
   ctx.host = host;
diff --git a/src/node_url.cc b/src/node_url.cc
index 7df9461fdd25b1..50a9380d379648 100644
--- a/src/node_url.cc
+++ b/src/node_url.cc
@@ -59,10 +59,12 @@ static const char kEOL = -1;
 // Used in ToUSVString().
 static const char16_t kUnicodeReplacementCharacter = 0xFFFD;
 
+// https://url.spec.whatwg.org/#concept-host
 union url_host_value {
   std::string domain;
   uint32_t ipv4;
   uint16_t ipv6[8];
+  std::string opaque;
   ~url_host_value() {}
 };
 
@@ -70,7 +72,8 @@ enum url_host_type {
   HOST_TYPE_FAILED = -1,
   HOST_TYPE_DOMAIN = 0,
   HOST_TYPE_IPV4 = 1,
-  HOST_TYPE_IPV6 = 2
+  HOST_TYPE_IPV6 = 2,
+  HOST_TYPE_OPAQUE = 3,
 };
 
 struct url_host {
@@ -151,6 +154,13 @@ static inline T ASCIILowercase(T ch) {
   return IsASCIIAlpha(ch) ? (ch | 0x20) : ch;
 }
 
+// https://url.spec.whatwg.org/#forbidden-host-code-point
+CHAR_TEST(8, IsForbiddenHostCodePoint,
+          ch == '\0' || ch == '\t' || ch == '\n' || ch == '\r' ||
+          ch == ' ' || ch == '#' || ch == '%' || ch == '/' ||
+          ch == ':' || ch == '?' || ch == '@' || ch == '[' ||
+          ch == '\\' || ch == ']')
+
 // https://url.spec.whatwg.org/#windows-drive-letter
 TWO_CHAR_STRING_TEST(8, IsWindowsDriveLetter,
                      (IsASCIIAlpha(ch1) && (ch2 == ':' || ch2 == '|')))
@@ -206,7 +216,7 @@ static const char* hex[256] = {
   "%F8", "%F9", "%FA", "%FB", "%FC", "%FD", "%FE", "%FF"
 };
 
-static const uint8_t SIMPLE_ENCODE_SET[32] = {
+static const uint8_t C0_CONTROL_ENCODE_SET[32] = {
   // 00     01     02     03     04     05     06     07
     0x01 | 0x02 | 0x04 | 0x08 | 0x10 | 0x20 | 0x40 | 0x80,
   // 08     09     0A     0B     0C     0D     0E     0F
@@ -273,7 +283,7 @@ static const uint8_t SIMPLE_ENCODE_SET[32] = {
     0x01 | 0x02 | 0x04 | 0x08 | 0x10 | 0x20 | 0x40 | 0x80
 };
 
-static const uint8_t DEFAULT_ENCODE_SET[32] = {
+static const uint8_t PATH_ENCODE_SET[32] = {
   // 00     01     02     03     04     05     06     07
     0x01 | 0x02 | 0x04 | 0x08 | 0x10 | 0x20 | 0x40 | 0x80,
   // 08     09     0A     0B     0C     0D     0E     0F
@@ -756,8 +766,8 @@ static url_host_type ParseIPv4Host(url_host* host,
     if (ch == '.' || ch == kEOL) {
       if (++parts > 4)
         goto end;
-      if (pointer - mark == 0)
-        break;
+      if (pointer == mark)
+        goto end;
       int64_t n = ParseNumber(mark, pointer);
       if (n < 0)
         goto end;
@@ -797,9 +807,32 @@ static url_host_type ParseIPv4Host(url_host* host,
   return type;
 }
 
+static url_host_type ParseOpaqueHost(url_host* host,
+                                     const char* input,
+                                     size_t length) {
+  url_host_type type = HOST_TYPE_OPAQUE;
+  std::string output;
+  output.reserve(length * 3);
+  for (size_t i = 0; i < length; i++) {
+    const char ch = input[i];
+    if (ch != '%' && IsForbiddenHostCodePoint(ch)) {
+      type = HOST_TYPE_FAILED;
+      goto end;
+    } else {
+      AppendOrEscape(&output, ch, C0_CONTROL_ENCODE_SET);
+    }
+  }
+
+  host->value.opaque = output;
+ end:
+  host->type = type;
+  return type;
+}
+
 static url_host_type ParseHost(url_host* host,
                                const char* input,
                                size_t length,
+                               bool is_special,
                                bool unicode = false) {
   url_host_type type = HOST_TYPE_FAILED;
   const char* pointer = input;
@@ -814,6 +847,9 @@ static url_host_type ParseHost(url_host* host,
     return ParseIPv6Host(host, ++pointer, length - 2);
   }
 
+  if (!is_special)
+    return ParseOpaqueHost(host, input, length);
+
   // First, we have to percent decode
   PercentDecode(input, length, &decoded);
 
@@ -824,10 +860,7 @@ static url_host_type ParseHost(url_host* host,
   // If any of the following characters are still present, we have to fail
   for (size_t n = 0; n < decoded.size(); n++) {
     const char ch = decoded[n];
-    if (ch == 0x00 || ch == 0x09 || ch == 0x0a || ch == 0x0d ||
-        ch == 0x20 || ch == '#' || ch == '%' || ch == '/' ||
-        ch == '?' || ch == '@' || ch == '[' || ch == '\\' ||
-        ch == ']') {
+    if (IsForbiddenHostCodePoint(ch)) {
       goto end;
     }
   }
@@ -907,14 +940,17 @@ static url_host_type WriteHost(url_host* host, std::string* dest) {
       uint16_t* start = &host->value.ipv6[0];
       uint16_t* compress_pointer =
           FindLongestZeroSequence(start, 8);
+      bool ignore0 = false;
       for (int n = 0; n <= 7; n++) {
         uint16_t* piece = &host->value.ipv6[n];
+        if (ignore0 && *piece == 0)
+          continue;
+        else if (ignore0)
+          ignore0 = false;
         if (compress_pointer == piece) {
           *dest += n == 0 ? "::" : ":";
-          while (*piece == 0 && ++n < 8)
-            piece = &host->value.ipv6[n];
-          if (n == 8)
-            break;
+          ignore0 = true;
+          continue;
         }
         char buf[5];
         char* buffer = buf;
@@ -926,6 +962,9 @@ static url_host_type WriteHost(url_host* host, std::string* dest) {
       *dest += ']';
       break;
     }
+    case HOST_TYPE_OPAQUE:
+      *dest = host->value.opaque;
+      break;
     case HOST_TYPE_FAILED:
       break;
   }
@@ -934,11 +973,14 @@ static url_host_type WriteHost(url_host* host, std::string* dest) {
 
 static bool ParseHost(std::string* input,
                       std::string* output,
+                      bool is_special,
                       bool unicode = false) {
-  if (input->length() == 0)
+  if (input->length() == 0) {
+    output->clear();
     return true;
+  }
   url_host host{{""}, HOST_TYPE_DOMAIN};
-  ParseHost(&host, input->c_str(), input->length(), unicode);
+  ParseHost(&host, input->c_str(), input->length(), is_special, unicode);
   if (host.type == HOST_TYPE_FAILED)
     return false;
   WriteHost(&host, output);
@@ -1006,6 +1048,12 @@ static inline void HarvestContext(Environment* env,
       context->flags |= URL_FLAGS_SPECIAL;
     if (_flags & URL_FLAGS_CANNOT_BE_BASE)
       context->flags |= URL_FLAGS_CANNOT_BE_BASE;
+    if (_flags & URL_FLAGS_HAS_USERNAME)
+      context->flags |= URL_FLAGS_HAS_USERNAME;
+    if (_flags & URL_FLAGS_HAS_PASSWORD)
+      context->flags |= URL_FLAGS_HAS_PASSWORD;
+    if (_flags & URL_FLAGS_HAS_HOST)
+      context->flags |= URL_FLAGS_HAS_HOST;
   }
   Local<Value> scheme = GET(env, context_obj, "scheme");
   if (scheme->IsString()) {
@@ -1015,6 +1063,23 @@ static inline void HarvestContext(Environment* env,
   Local<Value> port = GET(env, context_obj, "port");
   if (port->IsInt32())
     context->port = port->Int32Value(env->context()).FromJust();
+  if (context->flags & URL_FLAGS_HAS_USERNAME) {
+    Local<Value> username = GET(env, context_obj, "username");
+    CHECK(username->IsString());
+    Utf8Value value(env->isolate(), username);
+    context->username.assign(*value, value.length());
+  }
+  if (context->flags & URL_FLAGS_HAS_PASSWORD) {
+    Local<Value> password = GET(env, context_obj, "password");
+    CHECK(password->IsString());
+    Utf8Value value(env->isolate(), password);
+    context->password.assign(*value, value.length());
+  }
+  Local<Value> host = GET(env, context_obj, "host");
+  if (host->IsString()) {
+    Utf8Value value(env->isolate(), host);
+    context->host.assign(*value, value.length());
+  }
 }
 
 // Single dot segment can be ".", "%2e", or "%2E"
@@ -1077,7 +1142,6 @@ void URL::Parse(const char* input,
   bool atflag = false;
   bool sbflag = false;
   bool uflag = false;
-  bool base_is_file = false;
   int wskip = 0;
 
   std::string buffer;
@@ -1137,25 +1201,40 @@ void URL::Parse(const char* input,
       case kScheme:
         if (IsASCIIAlphanumeric(ch) || ch == '+' || ch == '-' || ch == '.') {
           buffer += ASCIILowercase(ch);
-          p++;
-          continue;
         } else if (ch == ':' || (has_state_override && ch == kEOL)) {
-          if (buffer.size() > 0) {
-            buffer += ':';
-            url->scheme = buffer;
-          } else if (has_state_override) {
+          if (has_state_override && buffer.size() == 0) {
             url->flags |= URL_FLAGS_TERMINATED;
             return;
           }
-          if (IsSpecial(url->scheme)) {
+          buffer += ':';
+
+          bool new_is_special = IsSpecial(buffer);
+
+          if (has_state_override) {
+            if ((special != new_is_special) ||
+                ((buffer == "file:") &&
+                 ((url->flags & URL_FLAGS_HAS_USERNAME) ||
+                  (url->flags & URL_FLAGS_HAS_PASSWORD) ||
+                  (url->port != -1)))) {
+              url->flags |= URL_FLAGS_TERMINATED;
+              return;
+            }
+
+            // File scheme && (host == empty or null) check left to JS-land
+            // as it can be done before even entering C++ binding.
+          }
+
+          url->scheme = buffer;
+          if (new_is_special) {
             url->flags |= URL_FLAGS_SPECIAL;
             special = true;
           } else {
             url->flags &= ~URL_FLAGS_SPECIAL;
+            special = false;
           }
+          buffer.clear();
           if (has_state_override)
             return;
-          buffer.clear();
           if (url->scheme == "file:") {
             state = kFile;
           } else if (special &&
@@ -1195,6 +1274,7 @@ void URL::Parse(const char* input,
             special = true;
           } else {
             url->flags &= ~URL_FLAGS_SPECIAL;
+            special = false;
           }
           if (base->flags & URL_FLAGS_HAS_PATH) {
             url->flags |= URL_FLAGS_HAS_PATH;
@@ -1246,6 +1326,7 @@ void URL::Parse(const char* input,
           special = true;
         } else {
           url->flags &= ~URL_FLAGS_SPECIAL;
+          special = false;
         }
         switch (ch) {
           case kEOL:
@@ -1414,6 +1495,10 @@ void URL::Parse(const char* input,
                    ch == '?' ||
                    ch == '#' ||
                    special_back_slash) {
+          if (atflag && buffer.size() == 0) {
+            url->flags |= URL_FLAGS_FAILED;
+            return;
+          }
           p -= buffer.size() + 1 + wskip;
           buffer.clear();
           state = kHost;
@@ -1423,13 +1508,16 @@ void URL::Parse(const char* input,
         break;
       case kHost:
       case kHostname:
-        if (ch == ':' && !sbflag) {
-          if (special && buffer.size() == 0) {
+        if (has_state_override && url->scheme == "file:") {
+          state = kFileHost;
+          continue;
+        } else if (ch == ':' && !sbflag) {
+          if (buffer.size() == 0) {
             url->flags |= URL_FLAGS_FAILED;
             return;
           }
           url->flags |= URL_FLAGS_HAS_HOST;
-          if (!ParseHost(&buffer, &url->host)) {
+          if (!ParseHost(&buffer, &url->host, special)) {
             url->flags |= URL_FLAGS_FAILED;
             return;
           }
@@ -1448,8 +1536,15 @@ void URL::Parse(const char* input,
             url->flags |= URL_FLAGS_FAILED;
             return;
           }
+          if (has_state_override &&
+              buffer.size() == 0 &&
+              ((url->username.size() > 0 || url->password.size() > 0) ||
+               url->port != -1)) {
+            url->flags |= URL_FLAGS_TERMINATED;
+            return;
+          }
           url->flags |= URL_FLAGS_HAS_HOST;
-          if (!ParseHost(&buffer, &url->host)) {
+          if (!ParseHost(&buffer, &url->host, special)) {
             url->flags |= URL_FLAGS_FAILED;
             return;
           }
@@ -1463,7 +1558,7 @@ void URL::Parse(const char* input,
             sbflag = true;
           if (ch == ']')
             sbflag = false;
-          buffer += ASCIILowercase(ch);
+          buffer += ch;
         }
         break;
       case kPort:
@@ -1508,12 +1603,12 @@ void URL::Parse(const char* input,
         }
         break;
       case kFile:
-        base_is_file = (
-            has_base &&
-            base->scheme == "file:");
-        switch (ch) {
-          case kEOL:
-            if (base_is_file) {
+        url->scheme = "file:";
+        if (ch == '/' || ch == '\\') {
+          state = kFileSlash;
+        } else if (has_base && base->scheme == "file:") {
+          switch (ch) {
+            case kEOL:
               if (base->flags & URL_FLAGS_HAS_HOST) {
                 url->flags |= URL_FLAGS_HAS_HOST;
                 url->host = base->host;
@@ -1527,15 +1622,7 @@ void URL::Parse(const char* input,
                 url->query = base->query;
               }
               break;
-            }
-            state = kPath;
-            continue;
-          case '\\':
-          case '/':
-            state = kFileSlash;
-            break;
-          case '?':
-            if (base_is_file) {
+            case '?':
               if (base->flags & URL_FLAGS_HAS_HOST) {
                 url->flags |= URL_FLAGS_HAS_HOST;
                 url->host = base->host;
@@ -1545,11 +1632,10 @@ void URL::Parse(const char* input,
                 url->path = base->path;
               }
               url->flags |= URL_FLAGS_HAS_QUERY;
+              url->query.clear();
               state = kQuery;
               break;
-            }
-          case '#':
-            if (base_is_file) {
+            case '#':
               if (base->flags & URL_FLAGS_HAS_HOST) {
                 url->flags |= URL_FLAGS_HAS_HOST;
                 url->host = base->host;
@@ -1562,29 +1648,33 @@ void URL::Parse(const char* input,
                 url->flags |= URL_FLAGS_HAS_QUERY;
                 url->query = base->query;
               }
+              url->flags |= URL_FLAGS_HAS_FRAGMENT;
+              url->fragment.clear();
               state = kFragment;
               break;
-            }
-          default:
-            if (base_is_file &&
-                (!IsWindowsDriveLetter(ch, p[1]) ||
-                 end - p == 1 ||
-                 (p[2] != '/' &&
-                  p[2] != '\\' &&
-                  p[2] != '?' &&
-                  p[2] != '#'))) {
-              if (base->flags & URL_FLAGS_HAS_HOST) {
-                url->flags |= URL_FLAGS_HAS_HOST;
-                url->host = base->host;
-              }
-              if (base->flags & URL_FLAGS_HAS_PATH) {
-                url->flags |= URL_FLAGS_HAS_PATH;
-                url->path = base->path;
+            default:
+              if ((!IsWindowsDriveLetter(ch, p[1]) ||
+                   end - p == 1 ||
+                   (p[2] != '/' &&
+                    p[2] != '\\' &&
+                    p[2] != '?' &&
+                    p[2] != '#'))) {
+                if (base->flags & URL_FLAGS_HAS_HOST) {
+                  url->flags |= URL_FLAGS_HAS_HOST;
+                  url->host = base->host;
+                }
+                if (base->flags & URL_FLAGS_HAS_PATH) {
+                  url->flags |= URL_FLAGS_HAS_PATH;
+                  url->path = base->path;
+                }
+                ShortenUrlPath(url);
               }
-              ShortenUrlPath(url);
-            }
-            state = kPath;
-            continue;
+              state = kPath;
+              continue;
+          }
+        } else {
+          state = kPath;
+          continue;
         }
         break;
       case kFileSlash:
@@ -1597,8 +1687,13 @@ void URL::Parse(const char* input,
               url->flags |= URL_FLAGS_HAS_PATH;
               url->path.push_back(base->path[0]);
             } else {
-              url->flags |= URL_FLAGS_HAS_HOST;
-              url->host = base->host;
+              if (base->flags & URL_FLAGS_HAS_HOST) {
+                url->flags |= URL_FLAGS_HAS_HOST;
+                url->host = base->host;
+              } else {
+                url->flags &= ~URL_FLAGS_HAS_HOST;
+                url->host.clear();
+              }
             }
           }
           state = kPath;
@@ -1611,19 +1706,28 @@ void URL::Parse(const char* input,
             ch == '\\' ||
             ch == '?' ||
             ch == '#') {
-          if (buffer.size() == 2 &&
+          if (!has_state_override &&
+              buffer.size() == 2 &&
               IsWindowsDriveLetter(buffer)) {
             state = kPath;
           } else if (buffer.size() == 0) {
+            url->flags |= URL_FLAGS_HAS_HOST;
+            url->host.clear();
+            if (has_state_override)
+              return;
             state = kPathStart;
           } else {
-            if (buffer != "localhost") {
-              url->flags |= URL_FLAGS_HAS_HOST;
-              if (!ParseHost(&buffer, &url->host)) {
-                url->flags |= URL_FLAGS_FAILED;
-                return;
-              }
+            std::string host;
+            if (!ParseHost(&buffer, &host, special)) {
+              url->flags |= URL_FLAGS_FAILED;
+              return;
             }
+            if (host == "localhost")
+              host.clear();
+            url->flags |= URL_FLAGS_HAS_HOST;
+            url->host = host;
+            if (has_state_override)
+              return;
             buffer.clear();
             state = kPathStart;
           }
@@ -1664,17 +1768,20 @@ void URL::Parse(const char* input,
               url->flags |= URL_FLAGS_HAS_PATH;
               url->path.push_back("");
             }
-          } else if (IsSingleDotSegment(buffer)) {
-            if (ch != '/' && !special_back_slash) {
-              url->flags |= URL_FLAGS_HAS_PATH;
-              url->path.push_back("");
-            }
+          } else if (IsSingleDotSegment(buffer) &&
+                     ch != '/' && !special_back_slash) {
+            url->flags |= URL_FLAGS_HAS_PATH;
+            url->path.push_back("");
           } else if (!IsSingleDotSegment(buffer)) {
             if (url->scheme == "file:" &&
                 url->path.empty() &&
                 buffer.size() == 2 &&
                 IsWindowsDriveLetter(buffer)) {
-              url->flags &= ~URL_FLAGS_HAS_HOST;
+              if ((url->flags & URL_FLAGS_HAS_HOST) &&
+                  !url->host.empty()) {
+                url->host.clear();
+                url->flags |= URL_FLAGS_HAS_HOST;
+              }
               buffer[1] = ':';
             }
             url->flags |= URL_FLAGS_HAS_PATH;
@@ -1697,7 +1804,7 @@ void URL::Parse(const char* input,
             state = kFragment;
           }
         } else {
-          AppendOrEscape(&buffer, ch, DEFAULT_ENCODE_SET);
+          AppendOrEscape(&buffer, ch, PATH_ENCODE_SET);
         }
         break;
       case kCannotBeBase:
@@ -1712,7 +1819,7 @@ void URL::Parse(const char* input,
             if (url->path.size() == 0)
               url->path.push_back("");
             if (url->path.size() > 0 && ch != kEOL)
-              AppendOrEscape(&url->path[0], ch, SIMPLE_ENCODE_SET);
+              AppendOrEscape(&url->path[0], ch, C0_CONTROL_ENCODE_SET);
         }
         break;
       case kQuery:
@@ -1735,7 +1842,7 @@ void URL::Parse(const char* input,
           case 0:
             break;
           default:
-            AppendOrEscape(&buffer, ch, SIMPLE_ENCODE_SET);
+            AppendOrEscape(&buffer, ch, C0_CONTROL_ENCODE_SET);
         }
         break;
       default:
@@ -1800,17 +1907,18 @@ static void Parse(Environment* env,
 
   // Define the return value placeholders
   const Local<Value> undef = Undefined(isolate);
+  const Local<Value> null = Null(isolate);
   if (!(url.flags & URL_FLAGS_FAILED)) {
     Local<Value> argv[9] = {
       undef,
       undef,
       undef,
       undef,
+      null,  // host defaults to null
+      null,  // port defaults to null
       undef,
-      undef,
-      undef,
-      undef,
-      undef,
+      null,  // query defaults to null
+      null,  // fragment defaults to null
     };
     SetArgs(env, argv, &url);
     (void)cb->Call(context, recv, arraysize(argv), argv);
@@ -1914,7 +2022,8 @@ static void DomainToASCII(const FunctionCallbackInfo<Value>& args) {
   Utf8Value value(env->isolate(), args[0]);
 
   url_host host{{""}, HOST_TYPE_DOMAIN};
-  ParseHost(&host, *value, value.length());
+  // Assuming the host is used for a special scheme.
+  ParseHost(&host, *value, value.length(), true);
   if (host.type == HOST_TYPE_FAILED) {
     args.GetReturnValue().Set(FIXED_ONE_BYTE_STRING(env->isolate(), ""));
     return;
@@ -1934,7 +2043,8 @@ static void DomainToUnicode(const FunctionCallbackInfo<Value>& args) {
   Utf8Value value(env->isolate(), args[0]);
 
   url_host host{{""}, HOST_TYPE_DOMAIN};
-  ParseHost(&host, *value, value.length(), true);
+  // Assuming the host is used for a special scheme.
+  ParseHost(&host, *value, value.length(), true, true);
   if (host.type == HOST_TYPE_FAILED) {
     args.GetReturnValue().Set(FIXED_ONE_BYTE_STRING(env->isolate(), ""));
     return;
@@ -1957,6 +2067,7 @@ const Local<Value> URL::ToObject(Environment* env) const {
   Context::Scope context_scope(context);
 
   const Local<Value> undef = Undefined(isolate);
+  const Local<Value> null = Null(isolate);
 
   if (context_.flags & URL_FLAGS_FAILED)
     return Local<Value>();
@@ -1966,11 +2077,11 @@ const Local<Value> URL::ToObject(Environment* env) const {
     undef,
     undef,
     undef,
+    null,  // host defaults to null
+    null,  // port defaults to null
     undef,
-    undef,
-    undef,
-    undef,
-    undef,
+    null,  // query defaults to null
+    null,  // fragment defaults to null
   };
   SetArgs(env, argv, &context_);
 
diff --git a/test/fixtures/url-setter-tests.js b/test/fixtures/url-setter-tests.js
index f537075674b77a..42580312c25bc3 100644
--- a/test/fixtures/url-setter-tests.js
+++ b/test/fixtures/url-setter-tests.js
@@ -370,14 +370,14 @@ module.exports =
                 "username": "wario"
             }
         },
-        // {
-        //     "href": "file://test/",
-        //     "new_value": "test",
-        //     "expected": {
-        //         "href": "file://test/",
-        //         "username": ""
-        //     }
-        // }
+        {
+            "href": "file://test/",
+            "new_value": "test",
+            "expected": {
+                "href": "file://test/",
+                "username": ""
+            }
+        }
     ],
     "password": [
         {
@@ -473,14 +473,14 @@ module.exports =
                 "password": "bowser"
             }
         },
-        // {
-        //     "href": "file://test/",
-        //     "new_value": "test",
-        //     "expected": {
-        //         "href": "file://test/",
-        //         "password": ""
-        //     }
-        // }
+        {
+            "href": "file://test/",
+            "new_value": "test",
+            "expected": {
+                "href": "file://test/",
+                "password": ""
+            }
+        }
     ],
     "host": [
         {
@@ -493,33 +493,33 @@ module.exports =
                 "hostname": "x"
             }
         },
-        // {
-        //     "href": "sc://x/",
-        //     "new_value": "\u0009",
-        //     "expected": {
-        //         "href": "sc:///",
-        //         "host": "",
-        //         "hostname": ""
-        //     }
-        // },
-        // {
-        //     "href": "sc://x/",
-        //     "new_value": "\u000A",
-        //     "expected": {
-        //         "href": "sc:///",
-        //         "host": "",
-        //         "hostname": ""
-        //     }
-        // },
-        // {
-        //     "href": "sc://x/",
-        //     "new_value": "\u000D",
-        //     "expected": {
-        //         "href": "sc:///",
-        //         "host": "",
-        //         "hostname": ""
-        //     }
-        // },
+        {
+            "href": "sc://x/",
+            "new_value": "\u0009",
+            "expected": {
+                "href": "sc:///",
+                "host": "",
+                "hostname": ""
+            }
+        },
+        {
+            "href": "sc://x/",
+            "new_value": "\u000A",
+            "expected": {
+                "href": "sc:///",
+                "host": "",
+                "hostname": ""
+            }
+        },
+        {
+            "href": "sc://x/",
+            "new_value": "\u000D",
+            "expected": {
+                "href": "sc:///",
+                "host": "",
+                "hostname": ""
+            }
+        },
         {
             "href": "sc://x/",
             "new_value": " ",
@@ -529,33 +529,33 @@ module.exports =
                 "hostname": "x"
             }
         },
-        // {
-        //     "href": "sc://x/",
-        //     "new_value": "#",
-        //     "expected": {
-        //         "href": "sc:///",
-        //         "host": "",
-        //         "hostname": ""
-        //     }
-        // },
-        // {
-        //     "href": "sc://x/",
-        //     "new_value": "/",
-        //     "expected": {
-        //         "href": "sc:///",
-        //         "host": "",
-        //         "hostname": ""
-        //     }
-        // },
-        // {
-        //     "href": "sc://x/",
-        //     "new_value": "?",
-        //     "expected": {
-        //         "href": "sc:///",
-        //         "host": "",
-        //         "hostname": ""
-        //     }
-        // },
+        {
+            "href": "sc://x/",
+            "new_value": "#",
+            "expected": {
+                "href": "sc:///",
+                "host": "",
+                "hostname": ""
+            }
+        },
+        {
+            "href": "sc://x/",
+            "new_value": "/",
+            "expected": {
+                "href": "sc:///",
+                "host": "",
+                "hostname": ""
+            }
+        },
+        {
+            "href": "sc://x/",
+            "new_value": "?",
+            "expected": {
+                "href": "sc:///",
+                "host": "",
+                "hostname": ""
+            }
+        },
         {
             "href": "sc://x/",
             "new_value": "@",
@@ -565,15 +565,15 @@ module.exports =
                 "hostname": "x"
             }
         },
-        // {
-        //     "href": "sc://x/",
-        //     "new_value": "ß",
-        //     "expected": {
-        //         "href": "sc://%C3%9F/",
-        //         "host": "%C3%9F",
-        //         "hostname": "%C3%9F"
-        //     }
-        // },
+        {
+            "href": "sc://x/",
+            "new_value": "ß",
+            "expected": {
+                "href": "sc://%C3%9F/",
+                "host": "%C3%9F",
+                "hostname": "%C3%9F"
+            }
+        },
         {
             "comment": "IDNA Nontransitional_Processing",
             "href": "https://x/",
@@ -916,56 +916,56 @@ module.exports =
                 "hostname": "example.net"
             }
         },
-        // {
-        //     "href": "file://y/",
-        //     "new_value": "x:123",
-        //     "expected": {
-        //         "href": "file://y/",
-        //         "host": "y",
-        //         "hostname": "y",
-        //         "port": ""
-        //     }
-        // },
-        // {
-        //     "href": "file://y/",
-        //     "new_value": "loc%41lhost",
-        //     "expected": {
-        //         "href": "file:///",
-        //         "host": "",
-        //         "hostname": "",
-        //         "port": ""
-        //     }
-        // },
-        // {
-        //     "href": "file://hi/x",
-        //     "new_value": "",
-        //     "expected": {
-        //         "href": "file:///x",
-        //         "host": "",
-        //         "hostname": "",
-        //         "port": ""
-        //     }
-        // },
-        // {
-        //     "href": "sc://test@test/",
-        //     "new_value": "",
-        //     "expected": {
-        //         "href": "sc://test@test/",
-        //         "host": "test",
-        //         "hostname": "test",
-        //         "username": "test"
-        //     }
-        // },
-        // {
-        //     "href": "sc://test:12/",
-        //     "new_value": "",
-        //     "expected": {
-        //         "href": "sc://test:12/",
-        //         "host": "test:12",
-        //         "hostname": "test",
-        //         "port": "12"
-        //     }
-        // }
+        {
+            "href": "file://y/",
+            "new_value": "x:123",
+            "expected": {
+                "href": "file://y/",
+                "host": "y",
+                "hostname": "y",
+                "port": ""
+            }
+        },
+        {
+            "href": "file://y/",
+            "new_value": "loc%41lhost",
+            "expected": {
+                "href": "file:///",
+                "host": "",
+                "hostname": "",
+                "port": ""
+            }
+        },
+        {
+            "href": "file://hi/x",
+            "new_value": "",
+            "expected": {
+                "href": "file:///x",
+                "host": "",
+                "hostname": "",
+                "port": ""
+            }
+        },
+        {
+            "href": "sc://test@test/",
+            "new_value": "",
+            "expected": {
+                "href": "sc://test@test/",
+                "host": "test",
+                "hostname": "test",
+                "username": "test"
+            }
+        },
+        {
+            "href": "sc://test:12/",
+            "new_value": "",
+            "expected": {
+                "href": "sc://test:12/",
+                "host": "test:12",
+                "hostname": "test",
+                "port": "12"
+            }
+        }
     ],
     "hostname": [
         {
@@ -978,33 +978,33 @@ module.exports =
                 "hostname": "x"
             }
         },
-        // {
-        //     "href": "sc://x/",
-        //     "new_value": "\u0009",
-        //     "expected": {
-        //         "href": "sc:///",
-        //         "host": "",
-        //         "hostname": ""
-        //     }
-        // },
-        // {
-        //     "href": "sc://x/",
-        //     "new_value": "\u000A",
-        //     "expected": {
-        //         "href": "sc:///",
-        //         "host": "",
-        //         "hostname": ""
-        //     }
-        // },
-        // {
-        //     "href": "sc://x/",
-        //     "new_value": "\u000D",
-        //     "expected": {
-        //         "href": "sc:///",
-        //         "host": "",
-        //         "hostname": ""
-        //     }
-        // },
+        {
+            "href": "sc://x/",
+            "new_value": "\u0009",
+            "expected": {
+                "href": "sc:///",
+                "host": "",
+                "hostname": ""
+            }
+        },
+        {
+            "href": "sc://x/",
+            "new_value": "\u000A",
+            "expected": {
+                "href": "sc:///",
+                "host": "",
+                "hostname": ""
+            }
+        },
+        {
+            "href": "sc://x/",
+            "new_value": "\u000D",
+            "expected": {
+                "href": "sc:///",
+                "host": "",
+                "hostname": ""
+            }
+        },
         {
             "href": "sc://x/",
             "new_value": " ",
@@ -1014,33 +1014,33 @@ module.exports =
                 "hostname": "x"
             }
         },
-        // {
-        //     "href": "sc://x/",
-        //     "new_value": "#",
-        //     "expected": {
-        //         "href": "sc:///",
-        //         "host": "",
-        //         "hostname": ""
-        //     }
-        // },
-        // {
-        //     "href": "sc://x/",
-        //     "new_value": "/",
-        //     "expected": {
-        //         "href": "sc:///",
-        //         "host": "",
-        //         "hostname": ""
-        //     }
-        // },
-        // {
-        //     "href": "sc://x/",
-        //     "new_value": "?",
-        //     "expected": {
-        //         "href": "sc:///",
-        //         "host": "",
-        //         "hostname": ""
-        //     }
-        // },
+        {
+            "href": "sc://x/",
+            "new_value": "#",
+            "expected": {
+                "href": "sc:///",
+                "host": "",
+                "hostname": ""
+            }
+        },
+        {
+            "href": "sc://x/",
+            "new_value": "/",
+            "expected": {
+                "href": "sc:///",
+                "host": "",
+                "hostname": ""
+            }
+        },
+        {
+            "href": "sc://x/",
+            "new_value": "?",
+            "expected": {
+                "href": "sc:///",
+                "host": "",
+                "hostname": ""
+            }
+        },
         {
             "href": "sc://x/",
             "new_value": "@",
@@ -1250,56 +1250,56 @@ module.exports =
                 "hostname": "example.net"
             }
         },
-        // {
-        //     "href": "file://y/",
-        //     "new_value": "x:123",
-        //     "expected": {
-        //         "href": "file://y/",
-        //         "host": "y",
-        //         "hostname": "y",
-        //         "port": ""
-        //     }
-        // },
-        // {
-        //     "href": "file://y/",
-        //     "new_value": "loc%41lhost",
-        //     "expected": {
-        //         "href": "file:///",
-        //         "host": "",
-        //         "hostname": "",
-        //         "port": ""
-        //     }
-        // },
-        // {
-        //     "href": "file://hi/x",
-        //     "new_value": "",
-        //     "expected": {
-        //         "href": "file:///x",
-        //         "host": "",
-        //         "hostname": "",
-        //         "port": ""
-        //     }
-        // },
-        // {
-        //     "href": "sc://test@test/",
-        //     "new_value": "",
-        //     "expected": {
-        //         "href": "sc://test@test/",
-        //         "host": "test",
-        //         "hostname": "test",
-        //         "username": "test"
-        //     }
-        // },
-        // {
-        //     "href": "sc://test:12/",
-        //     "new_value": "",
-        //     "expected": {
-        //         "href": "sc://test:12/",
-        //         "host": "test:12",
-        //         "hostname": "test",
-        //         "port": "12"
-        //     }
-        // }
+        {
+            "href": "file://y/",
+            "new_value": "x:123",
+            "expected": {
+                "href": "file://y/",
+                "host": "y",
+                "hostname": "y",
+                "port": ""
+            }
+        },
+        {
+            "href": "file://y/",
+            "new_value": "loc%41lhost",
+            "expected": {
+                "href": "file:///",
+                "host": "",
+                "hostname": "",
+                "port": ""
+            }
+        },
+        {
+            "href": "file://hi/x",
+            "new_value": "",
+            "expected": {
+                "href": "file:///x",
+                "host": "",
+                "hostname": "",
+                "port": ""
+            }
+        },
+        {
+            "href": "sc://test@test/",
+            "new_value": "",
+            "expected": {
+                "href": "sc://test@test/",
+                "host": "test",
+                "hostname": "test",
+                "username": "test"
+            }
+        },
+        {
+            "href": "sc://test:12/",
+            "new_value": "",
+            "expected": {
+                "href": "sc://test:12/",
+                "host": "test:12",
+                "hostname": "test",
+                "port": "12"
+            }
+        }
     ],
     "port": [
         {
diff --git a/test/fixtures/url-tests.js b/test/fixtures/url-tests.js
index d44a36bcfe7e13..69d289bd065557 100644
--- a/test/fixtures/url-tests.js
+++ b/test/fixtures/url-tests.js
@@ -1045,16 +1045,16 @@ module.exports =
     "search": "",
     "hash": ""
   },
-  // {
-  //   "input": "file://example:1/",
-  //   "base": "about:blank",
-  //   "failure": true
-  // },
-  // {
-  //   "input": "file://example:test/",
-  //   "base": "about:blank",
-  //   "failure": true
-  // },
+  {
+    "input": "file://example:1/",
+    "base": "about:blank",
+    "failure": true
+  },
+  {
+    "input": "file://example:test/",
+    "base": "about:blank",
+    "failure": true
+  },
   {
     "input": "file://example%/",
     "base": "about:blank",
@@ -3674,35 +3674,35 @@ module.exports =
     "search": "",
     "hash": ""
   },
-  // {
-  //   "input": "https://faß.ExAmPlE/",
-  //   "base": "about:blank",
-  //   "href": "https://xn--fa-hia.example/",
-  //   "origin": "https://faß.example",
-  //   "protocol": "https:",
-  //   "username": "",
-  //   "password": "",
-  //   "host": "xn--fa-hia.example",
-  //   "hostname": "xn--fa-hia.example",
-  //   "port": "",
-  //   "pathname": "/",
-  //   "search": "",
-  //   "hash": ""
-  // },
-  // {
-  //   "input": "sc://faß.ExAmPlE/",
-  //   "base": "about:blank",
-  //   "href": "sc://fa%C3%9F.ExAmPlE/",
-  //   "protocol": "sc:",
-  //   "username": "",
-  //   "password": "",
-  //   "host": "fa%C3%9F.ExAmPlE",
-  //   "hostname": "fa%C3%9F.ExAmPlE",
-  //   "port": "",
-  //   "pathname": "/",
-  //   "search": "",
-  //   "hash": ""
-  // },
+  {
+    "input": "https://faß.ExAmPlE/",
+    "base": "about:blank",
+    "href": "https://xn--fa-hia.example/",
+    "origin": "https://faß.example",
+    "protocol": "https:",
+    "username": "",
+    "password": "",
+    "host": "xn--fa-hia.example",
+    "hostname": "xn--fa-hia.example",
+    "port": "",
+    "pathname": "/",
+    "search": "",
+    "hash": ""
+  },
+  {
+    "input": "sc://faß.ExAmPlE/",
+    "base": "about:blank",
+    "href": "sc://fa%C3%9F.ExAmPlE/",
+    "protocol": "sc:",
+    "username": "",
+    "password": "",
+    "host": "fa%C3%9F.ExAmPlE",
+    "hostname": "fa%C3%9F.ExAmPlE",
+    "port": "",
+    "pathname": "/",
+    "search": "",
+    "hash": ""
+  },
   "Invalid escaped characters should fail and the percents should be escaped. https://www.w3.org/Bugs/Public/show_bug.cgi?id=24191",
   {
     "input": "http://%zz%66%a.com",
@@ -4362,37 +4362,37 @@ module.exports =
     "search": "",
     "hash": ""
   },
-  // "# unknown schemes and their hosts",
-  // {
-  //   "input": "sc://ñ.test/",
-  //   "base": "about:blank",
-  //   "href": "sc://%C3%B1.test/",
-  //   "origin": "null",
-  //   "protocol": "sc:",
-  //   "username": "",
-  //   "password": "",
-  //   "host": "%C3%B1.test",
-  //   "hostname": "%C3%B1.test",
-  //   "port": "",
-  //   "pathname": "/",
-  //   "search": "",
-  //   "hash": ""
-  // },
-  // {
-  //   "input": "sc://\u001F!\"$&'()*+,-.;<=>^_`{|}~/",
-  //   "base": "about:blank",
-  //   "href": "sc://%1F!\"$&'()*+,-.;<=>^_`{|}~/",
-  //   "origin": "null",
-  //   "protocol": "sc:",
-  //   "username": "",
-  //   "password": "",
-  //   "host": "%1F!\"$&'()*+,-.;<=>^_`{|}~",
-  //   "hostname": "%1F!\"$&'()*+,-.;<=>^_`{|}~",
-  //   "port": "",
-  //   "pathname": "/",
-  //   "search": "",
-  //   "hash": ""
-  // },
+  "# unknown schemes and their hosts",
+  {
+    "input": "sc://ñ.test/",
+    "base": "about:blank",
+    "href": "sc://%C3%B1.test/",
+    "origin": "null",
+    "protocol": "sc:",
+    "username": "",
+    "password": "",
+    "host": "%C3%B1.test",
+    "hostname": "%C3%B1.test",
+    "port": "",
+    "pathname": "/",
+    "search": "",
+    "hash": ""
+  },
+  {
+    "input": "sc://\u001F!\"$&'()*+,-.;<=>^_`{|}~/",
+    "base": "about:blank",
+    "href": "sc://%1F!\"$&'()*+,-.;<=>^_`{|}~/",
+    "origin": "null",
+    "protocol": "sc:",
+    "username": "",
+    "password": "",
+    "host": "%1F!\"$&'()*+,-.;<=>^_`{|}~",
+    "hostname": "%1F!\"$&'()*+,-.;<=>^_`{|}~",
+    "port": "",
+    "pathname": "/",
+    "search": "",
+    "hash": ""
+  },
   {
     "input": "sc://\u0000/",
     "base": "about:blank",
@@ -4403,40 +4403,40 @@ module.exports =
     "base": "about:blank",
     "failure": true
   },
-  // {
-  //   "input": "sc://%/",
-  //   "base": "about:blank",
-  //   "href": "sc://%/",
-  //   "protocol": "sc:",
-  //   "username": "",
-  //   "password": "",
-  //   "host": "%",
-  //   "hostname": "%",
-  //   "port": "",
-  //   "pathname": "/",
-  //   "search": "",
-  //   "hash": ""
-  // },
-  // {
-  //   "input": "sc://@/",
-  //   "base": "about:blank",
-  //   "failure": true
-  // },
-  // {
-  //   "input": "sc://te@s:t@/",
-  //   "base": "about:blank",
-  //   "failure": true
-  // },
-  // {
-  //   "input": "sc://:/",
-  //   "base": "about:blank",
-  //   "failure": true
-  // },
-  // {
-  //   "input": "sc://:12/",
-  //   "base": "about:blank",
-  //   "failure": true
-  // },
+  {
+    "input": "sc://%/",
+    "base": "about:blank",
+    "href": "sc://%/",
+    "protocol": "sc:",
+    "username": "",
+    "password": "",
+    "host": "%",
+    "hostname": "%",
+    "port": "",
+    "pathname": "/",
+    "search": "",
+    "hash": ""
+  },
+  {
+    "input": "sc://@/",
+    "base": "about:blank",
+    "failure": true
+  },
+  {
+    "input": "sc://te@s:t@/",
+    "base": "about:blank",
+    "failure": true
+  },
+  {
+    "input": "sc://:/",
+    "base": "about:blank",
+    "failure": true
+  },
+  {
+    "input": "sc://:12/",
+    "base": "about:blank",
+    "failure": true
+  },
   {
     "input": "sc://[/",
     "base": "about:blank",
@@ -4452,21 +4452,21 @@ module.exports =
     "base": "about:blank",
     "failure": true
   },
-  // {
-  //   "input": "x",
-  //   "base": "sc://ñ",
-  //   "href": "sc://%C3%B1/x",
-  //   "origin": "null",
-  //   "protocol": "sc:",
-  //   "username": "",
-  //   "password": "",
-  //   "host": "%C3%B1",
-  //   "hostname": "%C3%B1",
-  //   "port": "",
-  //   "pathname": "/x",
-  //   "search": "",
-  //   "hash": ""
-  // },
+  {
+    "input": "x",
+    "base": "sc://ñ",
+    "href": "sc://%C3%B1/x",
+    "origin": "null",
+    "protocol": "sc:",
+    "username": "",
+    "password": "",
+    "host": "%C3%B1",
+    "hostname": "%C3%B1",
+    "port": "",
+    "pathname": "/x",
+    "search": "",
+    "hash": ""
+  },
   "# unknown schemes and backslashes",
   {
     "input": "sc:\\../",
@@ -5327,20 +5327,20 @@ module.exports =
     "search": "",
     "hash": ""
   },
-  // {
-  //   "input": "/..//localhost//pig",
-  //   "base": "file://lion/",
-  //   "href": "file://lion/localhost//pig",
-  //   "protocol": "file:",
-  //   "username": "",
-  //   "password": "",
-  //   "host": "lion",
-  //   "hostname": "lion",
-  //   "port": "",
-  //   "pathname": "/localhost//pig",
-  //   "search": "",
-  //   "hash": ""
-  // },
+  {
+    "input": "/..//localhost//pig",
+    "base": "file://lion/",
+    "href": "file://lion/localhost//pig",
+    "protocol": "file:",
+    "username": "",
+    "password": "",
+    "host": "lion",
+    "hostname": "lion",
+    "port": "",
+    "pathname": "/localhost//pig",
+    "search": "",
+    "hash": ""
+  },
   {
     "input": "file://",
     "base": "file://ape/",
@@ -5356,34 +5356,34 @@ module.exports =
     "hash": ""
   },
   "# File URLs with non-empty hosts",
-  // {
-  //   "input": "/rooibos",
-  //   "base": "file://tea/",
-  //   "href": "file://tea/rooibos",
-  //   "protocol": "file:",
-  //   "username": "",
-  //   "password": "",
-  //   "host": "tea",
-  //   "hostname": "tea",
-  //   "port": "",
-  //   "pathname": "/rooibos",
-  //   "search": "",
-  //   "hash": ""
-  // },
-  // {
-  //   "input": "/?chai",
-  //   "base": "file://tea/",
-  //   "href": "file://tea/?chai",
-  //   "protocol": "file:",
-  //   "username": "",
-  //   "password": "",
-  //   "host": "tea",
-  //   "hostname": "tea",
-  //   "port": "",
-  //   "pathname": "/",
-  //   "search": "?chai",
-  //   "hash": ""
-  // },
+  {
+    "input": "/rooibos",
+    "base": "file://tea/",
+    "href": "file://tea/rooibos",
+    "protocol": "file:",
+    "username": "",
+    "password": "",
+    "host": "tea",
+    "hostname": "tea",
+    "port": "",
+    "pathname": "/rooibos",
+    "search": "",
+    "hash": ""
+  },
+  {
+    "input": "/?chai",
+    "base": "file://tea/",
+    "href": "file://tea/?chai",
+    "protocol": "file:",
+    "username": "",
+    "password": "",
+    "host": "tea",
+    "hostname": "tea",
+    "port": "",
+    "pathname": "/",
+    "search": "?chai",
+    "hash": ""
+  },
   "# Windows drive letter quirk with not empty host",
   {
     "input": "file://example.net/C:/",
@@ -5567,109 +5567,109 @@ module.exports =
     "failure": true
   },
   "# Non-special-URL path tests",
-  // {
-  //   "input": "sc://ñ",
-  //   "base": "about:blank",
-  //   "href": "sc://%C3%B1",
-  //   "origin": "null",
-  //   "protocol": "sc:",
-  //   "username": "",
-  //   "password": "",
-  //   "host": "%C3%B1",
-  //   "hostname": "%C3%B1",
-  //   "port": "",
-  //   "pathname": "",
-  //   "search": "",
-  //   "hash": ""
-  // },
-  // {
-  //   "input": "sc://ñ?x",
-  //   "base": "about:blank",
-  //   "href": "sc://%C3%B1?x",
-  //   "origin": "null",
-  //   "protocol": "sc:",
-  //   "username": "",
-  //   "password": "",
-  //   "host": "%C3%B1",
-  //   "hostname": "%C3%B1",
-  //   "port": "",
-  //   "pathname": "",
-  //   "search": "?x",
-  //   "hash": ""
-  // },
-  // {
-  //   "input": "sc://ñ#x",
-  //   "base": "about:blank",
-  //   "href": "sc://%C3%B1#x",
-  //   "origin": "null",
-  //   "protocol": "sc:",
-  //   "username": "",
-  //   "password": "",
-  //   "host": "%C3%B1",
-  //   "hostname": "%C3%B1",
-  //   "port": "",
-  //   "pathname": "",
-  //   "search": "",
-  //   "hash": "#x"
-  // },
-  // {
-  //   "input": "#x",
-  //   "base": "sc://ñ",
-  //   "href": "sc://%C3%B1#x",
-  //   "origin": "null",
-  //   "protocol": "sc:",
-  //   "username": "",
-  //   "password": "",
-  //   "host": "%C3%B1",
-  //   "hostname": "%C3%B1",
-  //   "port": "",
-  //   "pathname": "",
-  //   "search": "",
-  //   "hash": "#x"
-  // },
-  // {
-  //   "input": "?x",
-  //   "base": "sc://ñ",
-  //   "href": "sc://%C3%B1?x",
-  //   "origin": "null",
-  //   "protocol": "sc:",
-  //   "username": "",
-  //   "password": "",
-  //   "host": "%C3%B1",
-  //   "hostname": "%C3%B1",
-  //   "port": "",
-  //   "pathname": "",
-  //   "search": "?x",
-  //   "hash": ""
-  // },
-  // {
-  //   "input": "sc://?",
-  //   "base": "about:blank",
-  //   "href": "sc://?",
-  //   "protocol": "sc:",
-  //   "username": "",
-  //   "password": "",
-  //   "host": "",
-  //   "hostname": "",
-  //   "port": "",
-  //   "pathname": "",
-  //   "search": "",
-  //   "hash": ""
-  // },
-  // {
-  //   "input": "sc://#",
-  //   "base": "about:blank",
-  //   "href": "sc://#",
-  //   "protocol": "sc:",
-  //   "username": "",
-  //   "password": "",
-  //   "host": "",
-  //   "hostname": "",
-  //   "port": "",
-  //   "pathname": "",
-  //   "search": "",
-  //   "hash": ""
-  // },
+  {
+    "input": "sc://ñ",
+    "base": "about:blank",
+    "href": "sc://%C3%B1",
+    "origin": "null",
+    "protocol": "sc:",
+    "username": "",
+    "password": "",
+    "host": "%C3%B1",
+    "hostname": "%C3%B1",
+    "port": "",
+    "pathname": "",
+    "search": "",
+    "hash": ""
+  },
+  {
+    "input": "sc://ñ?x",
+    "base": "about:blank",
+    "href": "sc://%C3%B1?x",
+    "origin": "null",
+    "protocol": "sc:",
+    "username": "",
+    "password": "",
+    "host": "%C3%B1",
+    "hostname": "%C3%B1",
+    "port": "",
+    "pathname": "",
+    "search": "?x",
+    "hash": ""
+  },
+  {
+    "input": "sc://ñ#x",
+    "base": "about:blank",
+    "href": "sc://%C3%B1#x",
+    "origin": "null",
+    "protocol": "sc:",
+    "username": "",
+    "password": "",
+    "host": "%C3%B1",
+    "hostname": "%C3%B1",
+    "port": "",
+    "pathname": "",
+    "search": "",
+    "hash": "#x"
+  },
+  {
+    "input": "#x",
+    "base": "sc://ñ",
+    "href": "sc://%C3%B1#x",
+    "origin": "null",
+    "protocol": "sc:",
+    "username": "",
+    "password": "",
+    "host": "%C3%B1",
+    "hostname": "%C3%B1",
+    "port": "",
+    "pathname": "",
+    "search": "",
+    "hash": "#x"
+  },
+  {
+    "input": "?x",
+    "base": "sc://ñ",
+    "href": "sc://%C3%B1?x",
+    "origin": "null",
+    "protocol": "sc:",
+    "username": "",
+    "password": "",
+    "host": "%C3%B1",
+    "hostname": "%C3%B1",
+    "port": "",
+    "pathname": "",
+    "search": "?x",
+    "hash": ""
+  },
+  {
+    "input": "sc://?",
+    "base": "about:blank",
+    "href": "sc://?",
+    "protocol": "sc:",
+    "username": "",
+    "password": "",
+    "host": "",
+    "hostname": "",
+    "port": "",
+    "pathname": "",
+    "search": "",
+    "hash": ""
+  },
+  {
+    "input": "sc://#",
+    "base": "about:blank",
+    "href": "sc://#",
+    "protocol": "sc:",
+    "username": "",
+    "password": "",
+    "host": "",
+    "hostname": "",
+    "port": "",
+    "pathname": "",
+    "search": "",
+    "hash": ""
+  },
   {
     "input": "///",
     "base": "sc://x/",
@@ -5893,34 +5893,34 @@ module.exports =
     "hash": ""
   },
   "# percent encoded hosts in non-special-URLs",
-  // {
-  //   "input": "non-special://%E2%80%A0/",
-  //   "base": "about:blank",
-  //   "href": "non-special://%E2%80%A0/",
-  //   "protocol": "non-special:",
-  //   "username": "",
-  //   "password": "",
-  //   "host": "%E2%80%A0",
-  //   "hostname": "%E2%80%A0",
-  //   "port": "",
-  //   "pathname": "/",
-  //   "search": "",
-  //   "hash": ""
-  // },
-  // {
-  //   "input": "non-special://H%4fSt/path",
-  //   "base": "about:blank",
-  //   "href": "non-special://H%4fSt/path",
-  //   "protocol": "non-special:",
-  //   "username": "",
-  //   "password": "",
-  //   "host": "H%4fSt",
-  //   "hostname": "H%4fSt",
-  //   "port": "",
-  //   "pathname": "/path",
-  //   "search": "",
-  //   "hash": ""
-  // },
+  {
+    "input": "non-special://%E2%80%A0/",
+    "base": "about:blank",
+    "href": "non-special://%E2%80%A0/",
+    "protocol": "non-special:",
+    "username": "",
+    "password": "",
+    "host": "%E2%80%A0",
+    "hostname": "%E2%80%A0",
+    "port": "",
+    "pathname": "/",
+    "search": "",
+    "hash": ""
+  },
+  {
+    "input": "non-special://H%4fSt/path",
+    "base": "about:blank",
+    "href": "non-special://H%4fSt/path",
+    "protocol": "non-special:",
+    "username": "",
+    "password": "",
+    "host": "H%4fSt",
+    "hostname": "H%4fSt",
+    "port": "",
+    "pathname": "/path",
+    "search": "",
+    "hash": ""
+  },
   "# IPv6 in non-special-URLs",
   {
     "input": "non-special://[1:2:0:0:5:0:0:0]/",