diff --git a/CHANGELOG.md b/CHANGELOG.md
index 782fa28d4b54..39b5c66ea85e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -27,6 +27,10 @@
     the system level timeout duration, a timeout may occur sooner than specified
     in 'timeout'.
 
+* `dart:core`
+  * The `Uri` class now correctly handles paths while running on Node.js on
+    Windows.
+
 ### Dart VM
 * Support for MIPS has been remvoed.
 
diff --git a/pkg/dev_compiler/tool/input_sdk/patch/core_patch.dart b/pkg/dev_compiler/tool/input_sdk/patch/core_patch.dart
index fb5447e02cd3..efd0bce54b0e 100644
--- a/pkg/dev_compiler/tool/input_sdk/patch/core_patch.dart
+++ b/pkg/dev_compiler/tool/input_sdk/patch/core_patch.dart
@@ -602,7 +602,13 @@ class Uri {
 @patch
 class _Uri {
   @patch
-  static bool get _isWindows => false;
+  static bool get _isWindows => _isWindowsCached;
+
+  static final bool _isWindowsCached = JS(
+      'bool',
+      'typeof process != "undefined" && '
+      'Object.prototype.toString.call(process) == "[object process]" && '
+      'process.platform == "win32"');
 
   // Matches a String that _uriEncodes to itself regardless of the kind of
   // component.  This corresponds to [_unreservedTable], i.e. characters that
diff --git a/sdk/lib/_internal/js_runtime/lib/core_patch.dart b/sdk/lib/_internal/js_runtime/lib/core_patch.dart
index b95f9f130bb4..7507985aa3ad 100644
--- a/sdk/lib/_internal/js_runtime/lib/core_patch.dart
+++ b/sdk/lib/_internal/js_runtime/lib/core_patch.dart
@@ -611,7 +611,13 @@ class Uri {
 @patch
 class _Uri {
   @patch
-  static bool get _isWindows => false;
+  static bool get _isWindows => _isWindowsCached;
+
+  static final bool _isWindowsCached = JS(
+      'bool',
+      'typeof process != "undefined" && '
+      'Object.prototype.toString.call(process) == "[object process]" && '
+      'process.platform == "win32"');
 
   // Matches a String that _uriEncodes to itself regardless of the kind of
   // component.  This corresponds to [_unreservedTable], i.e. characters that