diff --git a/layout/tools/reftest/runreftest.py b/layout/tools/reftest/runreftest.py
index dd73008216a0..1389845a4870 100644
--- a/layout/tools/reftest/runreftest.py
+++ b/layout/tools/reftest/runreftest.py
@@ -149,6 +149,7 @@ class RefTest(object):
             break
         dirs.add(path)
         path = os.path.split(path)[0]
+    mozinfo.find_and_update_from_json(*dirs)
 
   def getFullPath(self, path):
     "Get an absolute path relative to self.oldcwd."