--- a/testing/web-platform/harness/wptrunner/testloader.py
+++ b/testing/web-platform/harness/wptrunner/testloader.py
@@ -1,11 +1,11 @@
+import hashlib
 import json
 import os
-import sys
 import urlparse
 from abc import ABCMeta, abstractmethod
 from Queue import Empty
 from collections import defaultdict, OrderedDict, deque
 from multiprocessing import Queue
 
 import manifestinclude
 import manifestexpected
@@ -38,22 +38,24 @@ class Unchunked(TestChunker):
         assert self.total_chunks == 1
 
     def __call__(self, manifest):
         for item in manifest:
             yield item
 
 
 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
         so that anything in the same subdirectory beyond a depth of 3 is in the same
         group. So all tests in a/b/c, a/b/c/d and a/b/c/e will be grouped together
         and separate to tests in a/b/f
 
         Returns: tuple (ordered dict of {test_dir: PathData}, total estimated runtime)