diff --git a/flask/ctx.py b/flask/ctx.py
index 52eddcb2..f64ab04a 100644
--- a/flask/ctx.py
+++ b/flask/ctx.py
@@ -41,7 +41,7 @@ def after_this_request(f):
         @app.route('/')
         def index():
             @after_this_request
-            def add_header():
+            def add_header(response):
                 response.headers['X-Foo'] = 'Parachute'
                 return response
             return 'Hello World!'