diff --git a/api/controller/controller_util.py b/api/controller/controller_util.py
index 861e452..fa22fbf 100644
--- a/api/controller/controller_util.py
+++ b/api/controller/controller_util.py
@@ -47,6 +47,10 @@
   if use_flags:
     env['USE'] = ' '.join(use_flags)
 
+  # Make sure it'll use the local source to build chrome when we have it.
+  if chrome_root:
+    env['CHROME_ORIGIN'] = 'LOCAL_SOURCE'
+
   # TODO(saklein) Remove the default when fully integrated in recipes.
   env['FEATURES'] = 'separatedebug'
   if features: