diff --git a/util/cache.py b/util/cache.py
index 20c1a97c8..13c0949de 100644
--- a/util/cache.py
+++ b/util/cache.py
@@ -29,6 +29,7 @@ def no_cache(f):
   @wraps(f)
   def add_no_cache(*args, **kwargs):
     response = f(*args, **kwargs)
-    response.headers['Cache-Control'] = 'no-cache, no-store, must-revalidate'
+    if response is not None:
+      response.headers['Cache-Control'] = 'no-cache, no-store, must-revalidate'
     return response
   return add_no_cache