diff --git a/src/node_constants.cc b/src/node_constants.cc
index b6c7bf37a3ad86..753b8f8fe16602 100644
--- a/src/node_constants.cc
+++ b/src/node_constants.cc
@@ -1241,69 +1241,6 @@ void DefineCryptoConstants(Local<Object> target) {
   NODE_DEFINE_CONSTANT(target, INT_MAX);
 }
 
-void DefineZlibConstants(Local<Object> target) {
-  NODE_DEFINE_CONSTANT(target, Z_NO_FLUSH);
-  NODE_DEFINE_CONSTANT(target, Z_PARTIAL_FLUSH);
-  NODE_DEFINE_CONSTANT(target, Z_SYNC_FLUSH);
-  NODE_DEFINE_CONSTANT(target, Z_FULL_FLUSH);
-  NODE_DEFINE_CONSTANT(target, Z_FINISH);
-  NODE_DEFINE_CONSTANT(target, Z_BLOCK);
-
-  // return/error codes
-  NODE_DEFINE_CONSTANT(target, Z_OK);
-  NODE_DEFINE_CONSTANT(target, Z_STREAM_END);
-  NODE_DEFINE_CONSTANT(target, Z_NEED_DICT);
-  NODE_DEFINE_CONSTANT(target, Z_ERRNO);
-  NODE_DEFINE_CONSTANT(target, Z_STREAM_ERROR);
-  NODE_DEFINE_CONSTANT(target, Z_DATA_ERROR);
-  NODE_DEFINE_CONSTANT(target, Z_MEM_ERROR);
-  NODE_DEFINE_CONSTANT(target, Z_BUF_ERROR);
-  NODE_DEFINE_CONSTANT(target, Z_VERSION_ERROR);
-
-  NODE_DEFINE_CONSTANT(target, Z_NO_COMPRESSION);
-  NODE_DEFINE_CONSTANT(target, Z_BEST_SPEED);
-  NODE_DEFINE_CONSTANT(target, Z_BEST_COMPRESSION);
-  NODE_DEFINE_CONSTANT(target, Z_DEFAULT_COMPRESSION);
-  NODE_DEFINE_CONSTANT(target, Z_FILTERED);
-  NODE_DEFINE_CONSTANT(target, Z_HUFFMAN_ONLY);
-  NODE_DEFINE_CONSTANT(target, Z_RLE);
-  NODE_DEFINE_CONSTANT(target, Z_FIXED);
-  NODE_DEFINE_CONSTANT(target, Z_DEFAULT_STRATEGY);
-  NODE_DEFINE_CONSTANT(target, ZLIB_VERNUM);
-
-  enum node_zlib_mode {
-    NONE,
-    DEFLATE,
-    INFLATE,
-    GZIP,
-    GUNZIP,
-    DEFLATERAW,
-    INFLATERAW,
-    UNZIP
-  };
-
-  NODE_DEFINE_CONSTANT(target, DEFLATE);
-  NODE_DEFINE_CONSTANT(target, INFLATE);
-  NODE_DEFINE_CONSTANT(target, GZIP);
-  NODE_DEFINE_CONSTANT(target, GUNZIP);
-  NODE_DEFINE_CONSTANT(target, DEFLATERAW);
-  NODE_DEFINE_CONSTANT(target, INFLATERAW);
-  NODE_DEFINE_CONSTANT(target, UNZIP);
-
-  NODE_DEFINE_CONSTANT(target, Z_MIN_WINDOWBITS);
-  NODE_DEFINE_CONSTANT(target, Z_MAX_WINDOWBITS);
-  NODE_DEFINE_CONSTANT(target, Z_DEFAULT_WINDOWBITS);
-  NODE_DEFINE_CONSTANT(target, Z_MIN_CHUNK);
-  NODE_DEFINE_CONSTANT(target, Z_MAX_CHUNK);
-  NODE_DEFINE_CONSTANT(target, Z_DEFAULT_CHUNK);
-  NODE_DEFINE_CONSTANT(target, Z_MIN_MEMLEVEL);
-  NODE_DEFINE_CONSTANT(target, Z_MAX_MEMLEVEL);
-  NODE_DEFINE_CONSTANT(target, Z_DEFAULT_MEMLEVEL);
-  NODE_DEFINE_CONSTANT(target, Z_MIN_LEVEL);
-  NODE_DEFINE_CONSTANT(target, Z_MAX_LEVEL);
-  NODE_DEFINE_CONSTANT(target, Z_DEFAULT_LEVEL);
-}
-
 void DefineDLOpenConstants(Local<Object> target) {
 #ifdef RTLD_LAZY
   NODE_DEFINE_CONSTANT(target, RTLD_LAZY);
diff --git a/src/node_internals.h b/src/node_internals.h
index 9a34825b1e6df0..0c0b2e317620ce 100644
--- a/src/node_internals.h
+++ b/src/node_internals.h
@@ -936,6 +936,8 @@ void GetEGid(const v8::FunctionCallbackInfo<v8::Value>& args);
 void GetGroups(const v8::FunctionCallbackInfo<v8::Value>& args);
 #endif  // __POSIX__ && !defined(__ANDROID__) && !defined(__CloudABI__)
 
+void DefineZlibConstants(v8::Local<v8::Object> target);
+
 }  // namespace node
 
 void napi_module_register_by_symbol(v8::Local<v8::Object> exports,
diff --git a/src/node_zlib.cc b/src/node_zlib.cc
index 288fbd7bcc9bcf..d0cc54c9436582 100644
--- a/src/node_zlib.cc
+++ b/src/node_zlib.cc
@@ -773,6 +773,59 @@ void Initialize(Local<Object> target,
 }
 
 }  // anonymous namespace
+
+void DefineZlibConstants(Local<Object> target) {
+  NODE_DEFINE_CONSTANT(target, Z_NO_FLUSH);
+  NODE_DEFINE_CONSTANT(target, Z_PARTIAL_FLUSH);
+  NODE_DEFINE_CONSTANT(target, Z_SYNC_FLUSH);
+  NODE_DEFINE_CONSTANT(target, Z_FULL_FLUSH);
+  NODE_DEFINE_CONSTANT(target, Z_FINISH);
+  NODE_DEFINE_CONSTANT(target, Z_BLOCK);
+
+  // return/error codes
+  NODE_DEFINE_CONSTANT(target, Z_OK);
+  NODE_DEFINE_CONSTANT(target, Z_STREAM_END);
+  NODE_DEFINE_CONSTANT(target, Z_NEED_DICT);
+  NODE_DEFINE_CONSTANT(target, Z_ERRNO);
+  NODE_DEFINE_CONSTANT(target, Z_STREAM_ERROR);
+  NODE_DEFINE_CONSTANT(target, Z_DATA_ERROR);
+  NODE_DEFINE_CONSTANT(target, Z_MEM_ERROR);
+  NODE_DEFINE_CONSTANT(target, Z_BUF_ERROR);
+  NODE_DEFINE_CONSTANT(target, Z_VERSION_ERROR);
+
+  NODE_DEFINE_CONSTANT(target, Z_NO_COMPRESSION);
+  NODE_DEFINE_CONSTANT(target, Z_BEST_SPEED);
+  NODE_DEFINE_CONSTANT(target, Z_BEST_COMPRESSION);
+  NODE_DEFINE_CONSTANT(target, Z_DEFAULT_COMPRESSION);
+  NODE_DEFINE_CONSTANT(target, Z_FILTERED);
+  NODE_DEFINE_CONSTANT(target, Z_HUFFMAN_ONLY);
+  NODE_DEFINE_CONSTANT(target, Z_RLE);
+  NODE_DEFINE_CONSTANT(target, Z_FIXED);
+  NODE_DEFINE_CONSTANT(target, Z_DEFAULT_STRATEGY);
+  NODE_DEFINE_CONSTANT(target, ZLIB_VERNUM);
+
+  NODE_DEFINE_CONSTANT(target, DEFLATE);
+  NODE_DEFINE_CONSTANT(target, INFLATE);
+  NODE_DEFINE_CONSTANT(target, GZIP);
+  NODE_DEFINE_CONSTANT(target, GUNZIP);
+  NODE_DEFINE_CONSTANT(target, DEFLATERAW);
+  NODE_DEFINE_CONSTANT(target, INFLATERAW);
+  NODE_DEFINE_CONSTANT(target, UNZIP);
+
+  NODE_DEFINE_CONSTANT(target, Z_MIN_WINDOWBITS);
+  NODE_DEFINE_CONSTANT(target, Z_MAX_WINDOWBITS);
+  NODE_DEFINE_CONSTANT(target, Z_DEFAULT_WINDOWBITS);
+  NODE_DEFINE_CONSTANT(target, Z_MIN_CHUNK);
+  NODE_DEFINE_CONSTANT(target, Z_MAX_CHUNK);
+  NODE_DEFINE_CONSTANT(target, Z_DEFAULT_CHUNK);
+  NODE_DEFINE_CONSTANT(target, Z_MIN_MEMLEVEL);
+  NODE_DEFINE_CONSTANT(target, Z_MAX_MEMLEVEL);
+  NODE_DEFINE_CONSTANT(target, Z_DEFAULT_MEMLEVEL);
+  NODE_DEFINE_CONSTANT(target, Z_MIN_LEVEL);
+  NODE_DEFINE_CONSTANT(target, Z_MAX_LEVEL);
+  NODE_DEFINE_CONSTANT(target, Z_DEFAULT_LEVEL);
+}
+
 }  // namespace node
 
 NODE_BUILTIN_MODULE_CONTEXT_AWARE(zlib, node::Initialize)