diff --git a/testing/web-platform/harness/wptrunner/testloader.py b/testing/web-platform/harness/wptrunner/testloader.py
index 29a07c455220..baf09bde8acc 100644
--- a/testing/web-platform/harness/wptrunner/testloader.py
+++ b/testing/web-platform/harness/wptrunner/testloader.py
@@ -1,6 +1,6 @@
+import hashlib
 import json
 import os
-import sys
 import urlparse
 from abc import ABCMeta, abstractmethod
 from Queue import Empty
@@ -43,12 +43,14 @@ class Unchunked(TestChunker):
 
 
 class HashChunker(TestChunker):
-    def __call__(self):
+    def __call__(self, manifest):
         chunk_index = self.chunk_number - 1
         for test_path, tests in manifest:
-            if hash(test_path) % self.total_chunks == chunk_index:
+            h = int(hashlib.md5(test_path).hexdigest(), 16)
+            if h % self.total_chunks == chunk_index:
                 yield test_path, tests
 
+
 class EqualTimeChunker(TestChunker):
     def _group_by_directory(self, manifest_items):
         """Split the list of manifest items into a ordered dict that groups tests in