diff --git a/guides/source/action_controller_overview.md b/guides/source/action_controller_overview.md
index 7e0a8a43d409e66d6e7c4f5141fabbb2c2d93572..e01d0d57ea52a4d14c625514f24527a3f75e08f0 100644
--- a/guides/source/action_controller_overview.md
+++ b/guides/source/action_controller_overview.md
@@ -194,7 +194,7 @@ class PeopleController < ActionController::Base
 
   # This will pass with flying colors as long as there's a person key
   # in the parameters, otherwise it'll raise a
-  # ActionController::MissingParameter exception, which will get
+  # ActionController::ParameterMissing exception, which will get
   # caught by ActionController::Base and turned into that 400 Bad
   # Request reply.
   def update