diff --git a/tests/watchlists_unittest.py b/tests/watchlists_unittest.py
index ecc16e251..968de038f 100755
--- a/tests/watchlists_unittest.py
+++ b/tests/watchlists_unittest.py
@@ -5,6 +5,7 @@
 
 """Unit tests for watchlists.py."""
 
+import os
 import unittest
 import super_mox
 import watchlists
@@ -127,6 +128,32 @@ class WatchlistsTest(super_mox.SuperMoxTestBase):
     wl = watchlists.Watchlists('/a/path')
     self.assertEqual(wl.GetWatchersForPaths(['file_views_mac']), watchers)
 
+  def testWinPathWatchers(self):
+    """Test watchers for a windows path (containing backward slashes)."""
+    watchers = ['abc@def.com', 'x1@xyz.org']
+    contents = \
+      """{
+        'WATCHLIST_DEFINITIONS': {
+          'browser': {
+            'filepath': 'chrome/browser/.*',
+          },
+        },
+        'WATCHLISTS': {
+          'browser': %s,
+        },
+      } """ % watchers
+    saved_sep = os.sep
+    os.sep = '\\'  # to pose as win32
+    watchlists.Watchlists._HasWatchlistsFile().AndReturn(True)
+    watchlists.Watchlists._ContentsOfWatchlistsFile().AndReturn(contents)
+    self.mox.ReplayAll()
+
+    wl = watchlists.Watchlists(r'a\path')
+    returned_watchers = wl.GetWatchersForPaths(
+          [r'chrome\browser\renderer_host\render_widget_host.h'])
+    os.sep = saved_sep  # revert back os.sep before asserts
+    self.assertEqual(returned_watchers, watchers)
+
 
 if __name__ == '__main__':
   unittest.main()
diff --git a/watchlists.py b/watchlists.py
index 77b63eabc..9d38faf49 100755
--- a/watchlists.py
+++ b/watchlists.py
@@ -104,6 +104,7 @@ class Watchlists(object):
     """
     watchers = set()  # A set, to avoid duplicates
     for path in paths:
+      path = path.replace(os.sep, '/')
       for name, rule in self._defns.iteritems():
         if name not in self._watchlists: continue
         rex_str = rule.get('filepath')