1 files changed, 5 insertions, 0 deletions
diff --git a/actionpack/lib/action_dispatch/routing/route_set.rb b/actionpack/lib/action_dispatch/routing/route_set.rb
index 552d472afa..33eb7b0746 100644
--- a/actionpack/lib/action_dispatch/routing/route_set.rb
+++ b/actionpack/lib/action_dispatch/routing/route_set.rb
@@ -31,6 +31,7 @@ module ActionDispatch
         end
 
         def prepare_params!(params)
+          normalize_controller!(params)
           merge_default_action!(params)
           split_glob_param!(params) if @glob_param
         end
@@ -66,6 +67,10 @@ module ActionDispatch
           controller.action(action).call(env)
         end
 
+        def normalize_controller!(params)
+          params[:controller] = params[:controller].underscore if params.key?(:controller)
+        end
+
         def merge_default_action!(params)
           params[:action] ||= 'index'
         end