--- a/testing/tps/create_venv.py
+++ b/testing/tps/create_venv.py
@@ -116,17 +116,18 @@ def main():
         testdir = os.path.join(here, 'tests')
         extdir = os.path.join(here, 'extensions')
 
     assert(os.path.exists(testdir))
     assert(os.path.exists(extdir))
 
     # Update config file
     config_in_path = os.path.join(here, 'config', 'config.json.in')
-    replacements = {'__TESTDIR__': testdir, '__EXTENSIONDIR__': extdir}
+    replacements = {'__TESTDIR__': testdir.replace('\\','/'),
+                    '__EXTENSIONDIR__': extdir.replace('\\','/')}
     if options.username and options.password:
         replacements.update({
             '__FX_ACCOUNT_USERNAME__': options.username,
             '__FX_ACCOUNT_PASSWORD__': options.password})
     else:
         print 'Firefox Account credentials not specified. Please update the ' \
               'config file manually.'