diff --git a/runtime/tests/vm/dart_2/isolates/reload_utils.dart b/runtime/tests/vm/dart_2/isolates/reload_utils.dart
index 36f8fa9..853d2f0 100644
--- a/runtime/tests/vm/dart_2/isolates/reload_utils.dart
+++ b/runtime/tests/vm/dart_2/isolates/reload_utils.dart
@@ -25,7 +25,7 @@
     await File(testFile).writeAsString(version);
     final dillFile = path.join(tempDir, 'test.dart.${i++}.dill');
     await compile(testFile, dillFile);
-    dills.add(dillFile);
+    dills.add(Uri.file(dillFile).toString());
   }
   return dills;
 }