diff --git a/tools/distrib/check_include_guards.py b/tools/distrib/check_include_guards.py
index 9c23a70e001e8311466b747e047ebc5bc5798bb8..ef770b30b42ec53c010648f4671fd0fffaa39192 100755
--- a/tools/distrib/check_include_guards.py
+++ b/tools/distrib/check_include_guards.py
@@ -98,6 +98,7 @@ class GuardValidator(object):
     match = self.ifndef_re.search(fcontents)
     if not match:
       print 'something drastically wrong with: %s' % fpath
+      return False # failed
     if match.lastindex is None:
       # No ifndef. Request manual addition with hints
       self.fail(fpath, match.re, match.string, '', '', False)