diff --git a/benchmark/url/legacy-vs-whatwg-url-get-prop.js b/benchmark/url/legacy-vs-whatwg-url-get-prop.js
index 59bb4724f42ef3..16bcd226324ef8 100644
--- a/benchmark/url/legacy-vs-whatwg-url-get-prop.js
+++ b/benchmark/url/legacy-vs-whatwg-url-get-prop.js
@@ -26,7 +26,7 @@ function useLegacy(data) {
   // It's necessary to assign the values to an object
   // to avoid loop invariant code motion.
   bench.start();
-  for (var i = 0; i < len; i++) {
+  for (let i = 0; i < len; i++) {
     const obj = data[i];
     noDead.protocol = obj.protocol;
     noDead.auth = obj.auth;
@@ -55,7 +55,7 @@ function useWHATWG(data) {
   };
   const len = data.length;
   bench.start();
-  for (var i = 0; i < len; i++) {
+  for (let i = 0; i < len; i++) {
     const obj = data[i];
     noDead.protocol = obj.protocol;
     noDead.auth = `${obj.username}:${obj.password}`;
diff --git a/benchmark/url/legacy-vs-whatwg-url-parse.js b/benchmark/url/legacy-vs-whatwg-url-parse.js
index e3f50a76a45c77..7c49654b47d8e2 100644
--- a/benchmark/url/legacy-vs-whatwg-url-parse.js
+++ b/benchmark/url/legacy-vs-whatwg-url-parse.js
@@ -15,7 +15,7 @@ function useLegacy(data) {
   const len = data.length;
   var result = url.parse(data[0]);  // Avoid dead code elimination
   bench.start();
-  for (var i = 0; i < len; ++i) {
+  for (let i = 0; i < len; ++i) {
     result = url.parse(data[i]);
   }
   bench.end(len);
@@ -26,7 +26,7 @@ function useWHATWGWithBase(data) {
   const len = data.length;
   var result = new URL(data[0][0], data[0][1]);  // Avoid dead code elimination
   bench.start();
-  for (var i = 0; i < len; ++i) {
+  for (let i = 0; i < len; ++i) {
     const item = data[i];
     result = new URL(item[0], item[1]);
   }
@@ -38,7 +38,7 @@ function useWHATWGWithoutBase(data) {
   const len = data.length;
   var result = new URL(data[0]);  // Avoid dead code elimination
   bench.start();
-  for (var i = 0; i < len; ++i) {
+  for (let i = 0; i < len; ++i) {
     result = new URL(data[i]);
   }
   bench.end(len);
diff --git a/benchmark/url/legacy-vs-whatwg-url-searchparams-parse.js b/benchmark/url/legacy-vs-whatwg-url-searchparams-parse.js
index 81b5b6dc16ce24..f6037d332d0692 100644
--- a/benchmark/url/legacy-vs-whatwg-url-searchparams-parse.js
+++ b/benchmark/url/legacy-vs-whatwg-url-searchparams-parse.js
@@ -13,7 +13,7 @@ const bench = common.createBenchmark(main, {
 function useLegacy(n, input) {
   querystring.parse(input);
   bench.start();
-  for (var i = 0; i < n; i += 1) {
+  for (let i = 0; i < n; i += 1) {
     querystring.parse(input);
   }
   bench.end(n);
@@ -22,7 +22,7 @@ function useLegacy(n, input) {
 function useWHATWG(n, param) {
   new URLSearchParams(param);
   bench.start();
-  for (var i = 0; i < n; i += 1) {
+  for (let i = 0; i < n; i += 1) {
     new URLSearchParams(param);
   }
   bench.end(n);
diff --git a/benchmark/url/legacy-vs-whatwg-url-searchparams-serialize.js b/benchmark/url/legacy-vs-whatwg-url-searchparams-serialize.js
index f97961decf5069..cb2301e94036da 100644
--- a/benchmark/url/legacy-vs-whatwg-url-searchparams-serialize.js
+++ b/benchmark/url/legacy-vs-whatwg-url-searchparams-serialize.js
@@ -14,7 +14,7 @@ function useLegacy(n, input, prop) {
   const obj = querystring.parse(input);
   querystring.stringify(obj);
   bench.start();
-  for (var i = 0; i < n; i += 1) {
+  for (let i = 0; i < n; i += 1) {
     querystring.stringify(obj);
   }
   bench.end(n);
@@ -24,7 +24,7 @@ function useWHATWG(n, param, prop) {
   const obj = new URLSearchParams(param);
   obj.toString();
   bench.start();
-  for (var i = 0; i < n; i += 1) {
+  for (let i = 0; i < n; i += 1) {
     obj.toString();
   }
   bench.end(n);
diff --git a/benchmark/url/legacy-vs-whatwg-url-serialize.js b/benchmark/url/legacy-vs-whatwg-url-serialize.js
index e4c821cb2e2c1b..d6d8c8a4e71152 100644
--- a/benchmark/url/legacy-vs-whatwg-url-serialize.js
+++ b/benchmark/url/legacy-vs-whatwg-url-serialize.js
@@ -15,7 +15,7 @@ function useLegacy(data) {
   const len = data.length;
   var noDead = url.format(obj);
   bench.start();
-  for (var i = 0; i < len; i++) {
+  for (let i = 0; i < len; i++) {
     noDead = data[i].toString();
   }
   bench.end(len);
@@ -27,7 +27,7 @@ function useWHATWG(data) {
   const len = data.length;
   var noDead = obj.toString();
   bench.start();
-  for (var i = 0; i < len; i++) {
+  for (let i = 0; i < len; i++) {
     noDead = data[i].toString();
   }
   bench.end(len);
diff --git a/benchmark/url/url-format.js b/benchmark/url/url-format.js
index 14696af8e31c3f..3e91cefd363c37 100644
--- a/benchmark/url/url-format.js
+++ b/benchmark/url/url-format.js
@@ -21,7 +21,7 @@ function main({ type, n }) {
     url.format(inputs[name]);
 
   bench.start();
-  for (var i = 0; i < n; i += 1)
+  for (let i = 0; i < n; i += 1)
     url.format(input);
   bench.end(n);
 }
diff --git a/benchmark/url/url-parse.js b/benchmark/url/url-parse.js
index 83f626ccdadfe3..751a11201b11e2 100644
--- a/benchmark/url/url-parse.js
+++ b/benchmark/url/url-parse.js
@@ -16,7 +16,7 @@ function main({ type, n }) {
   const input = inputs[type] || '';
 
   bench.start();
-  for (var i = 0; i < n; i += 1)
+  for (let i = 0; i < n; i += 1)
     url.parse(input);
   bench.end(n);
 }
diff --git a/benchmark/url/url-resolve.js b/benchmark/url/url-resolve.js
index bd584c6f6090e9..9f6e958a00bba0 100644
--- a/benchmark/url/url-resolve.js
+++ b/benchmark/url/url-resolve.js
@@ -23,7 +23,7 @@ function main({ n, href, path }) {
   const p = paths[path];
 
   bench.start();
-  for (var i = 0; i < n; i += 1)
+  for (let i = 0; i < n; i += 1)
     url.resolve(h, p);
   bench.end(n);
 }
diff --git a/benchmark/url/url-searchparams-iteration.js b/benchmark/url/url-searchparams-iteration.js
index 244c95502bfffb..b628908d62c708 100644
--- a/benchmark/url/url-searchparams-iteration.js
+++ b/benchmark/url/url-searchparams-iteration.js
@@ -19,7 +19,7 @@ function forEach(n) {
   };
 
   bench.start();
-  for (var i = 0; i < n; i += 1)
+  for (let i = 0; i < n; i += 1)
     params.forEach(cb);
   bench.end(n);
 
@@ -32,7 +32,7 @@ function iterator(n) {
   const noDead = [];
 
   bench.start();
-  for (var i = 0; i < n; i += 1) {
+  for (let i = 0; i < n; i += 1) {
     for (const pair of params) {
       noDead[0] = pair[0];
       noDead[1] = pair[1];
diff --git a/benchmark/url/url-searchparams-read.js b/benchmark/url/url-searchparams-read.js
index 2eb0a4f21350dc..cdaaa7ad11a8c3 100644
--- a/benchmark/url/url-searchparams-read.js
+++ b/benchmark/url/url-searchparams-read.js
@@ -16,7 +16,7 @@ function main({ accessMethod, param, n }) {
     throw new Error(`Unknown method ${accessMethod}`);
 
   bench.start();
-  for (var i = 0; i < n; i += 1)
+  for (let i = 0; i < n; i += 1)
     params[accessMethod](param);
   bench.end(n);
 }
diff --git a/benchmark/url/url-searchparams-sort.js b/benchmark/url/url-searchparams-sort.js
index 0d4f605fa8edd6..5beb98cf2d2e25 100644
--- a/benchmark/url/url-searchparams-sort.js
+++ b/benchmark/url/url-searchparams-sort.js
@@ -39,7 +39,7 @@ function main({ type, n }) {
   const array = getParams(input);
 
   bench.start();
-  for (var i = 0; i < n; i++) {
+  for (let i = 0; i < n; i++) {
     params[searchParams] = array.slice();
     params.sort();
   }
diff --git a/benchmark/url/usvstring.js b/benchmark/url/usvstring.js
index 91abe8d67351c7..37141ff5512249 100644
--- a/benchmark/url/usvstring.js
+++ b/benchmark/url/usvstring.js
@@ -21,7 +21,7 @@ function main({ input, n }) {
   const str = inputs[input];
 
   bench.start();
-  for (var i = 0; i < n; i++)
+  for (let i = 0; i < n; i++)
     toUSVString(str);
   bench.end(n);
 }
diff --git a/benchmark/url/whatwg-url-idna.js b/benchmark/url/whatwg-url-idna.js
index b67a08da7a88e0..853a19776df5d2 100644
--- a/benchmark/url/whatwg-url-idna.js
+++ b/benchmark/url/whatwg-url-idna.js
@@ -36,7 +36,7 @@ function main({ n, to, domain }) {
   const method = to === 'ascii' ? domainToASCII : domainToUnicode;
 
   bench.start();
-  for (var i = 0; i < n; i++) {
+  for (let i = 0; i < n; i++) {
     method(value);
   }
   bench.end(n);
diff --git a/benchmark/url/whatwg-url-properties.js b/benchmark/url/whatwg-url-properties.js
index 6961fec49e5fee..60f573e27a8fe2 100644
--- a/benchmark/url/whatwg-url-properties.js
+++ b/benchmark/url/whatwg-url-properties.js
@@ -14,7 +14,7 @@ function setAndGet(data, prop) {
   const len = data.length;
   var result = data[0][prop];
   bench.start();
-  for (var i = 0; i < len; ++i) {
+  for (let i = 0; i < len; ++i) {
     result = data[i][prop];
     data[i][prop] = result;
   }
@@ -26,7 +26,7 @@ function get(data, prop) {
   const len = data.length;
   var result = data[0][prop];
   bench.start();
-  for (var i = 0; i < len; ++i) {
+  for (let i = 0; i < len; ++i) {
     result = data[i][prop]; // get
   }
   bench.end(len);