diff --git a/tests/_chrome/sample_test.dart b/tests/_chrome/sample_test.dart
index 85448ff4376..b25a94b9b3f 100644
--- a/tests/_chrome/sample_test.dart
+++ b/tests/_chrome/sample_test.dart
@@ -17,7 +17,7 @@ main() {
   test('fails from browser', () {
     // APIs should not work in standard browser apps.
     expect(() {
-      _chrome.app.window.create('foo.html');
+      _chrome.app.window.create('IntentionallyMissingFile.html');
     }, throws);
   });
 }
diff --git a/tests/html/audioelement_test.dart b/tests/html/audioelement_test.dart
index 28285962f84..02c89359bb1 100644
--- a/tests/html/audioelement_test.dart
+++ b/tests/html/audioelement_test.dart
@@ -13,9 +13,9 @@ main() {
     });
 
   test('constructorTest2', () {
-      var audio = new AudioElement('hahaURL');
+      var audio = new AudioElement('IntentionallyMissingFileURL');
       expect(audio, isNotNull);
       expect(audio is AudioElement, isTrue);
-      expect(audio.src, contains('hahaURL'));
+      expect(audio.src, contains('IntentionallyMissingFileURL'));
     });
 }
diff --git a/tools/testing/dart/http_server.dart b/tools/testing/dart/http_server.dart
index 14cb0ff8dbe..a5e7b8eba15 100644
--- a/tools/testing/dart/http_server.dart
+++ b/tools/testing/dart/http_server.dart
@@ -126,17 +126,7 @@ class TestingServers {
     "/foo",
     "/bar",
     "/NonExistingFile",
-    "/NonExistingFile.js",
-    "/hahaURL",
-    "/IntentionallyMissingFile",
-    "/IntentionallyMissingFile.dart",
-    "/IntentionallyMissingFile.html",
-    "/IntentionallyMissingFile.png",
-    "/IntentionallyMissingFile.css",
-    "/IntentionallyMissingFile.jpg",
-    "/IntentionallyMissingFile.ttf",
-    "/IntentionallyMissingFile.otf",
-    "/IntentionallyMissingFile.jpeg"
+    "IntentionallyMissingFile",
   ];
 
   List _serverList = [];
@@ -419,8 +409,8 @@ class TestingServers {
 
   void _sendNotFound(HttpRequest request) {
     bool isHarmlessPath(String path) {
-      return _HARMLESS_REQUEST_PATH_ENDINGS.any((ending) {
-        return path.endsWith(ending);
+      return _HARMLESS_REQUEST_PATH_ENDINGS.any((pattern) {
+        return path.contains(pattern);
       });
     }
     if (!isHarmlessPath(request.uri.path)) {