1 files changed, 12 insertions, 2 deletions
diff --git a/actionpack/lib/abstract_controller/helpers.rb b/actionpack/lib/abstract_controller/helpers.rb
index 95c67d482b..109eff10eb 100644
--- a/actionpack/lib/abstract_controller/helpers.rb
+++ b/actionpack/lib/abstract_controller/helpers.rb
@@ -150,7 +150,17 @@ module AbstractController
             rescue LoadError => e
               raise AbstractController::Helpers::MissingHelperError.new(e, file_name)
             end
-            file_name.camelize.constantize
+
+            mod_name = file_name.camelize
+            begin
+              mod_name.constantize
+            rescue LoadError
+              # dependencies.rb gives a similar error message but its wording is
+              # not as clear because it mentions autoloading. To the user all it
+              # matters is that a helper module couldn't be loaded, autoloading
+              # is an internal mechanism that should not leak.
+              raise NameError, "Couldn't find #{mod_name}, expected it to be defined in helpers/#{file_name}.rb"
+            end
           when Module
             arg
           else
@@ -174,7 +184,7 @@ module AbstractController
         module_name = name.sub(/Controller$/, '')
         module_path = module_name.underscore
         helper module_path
-      rescue MissingSourceFile => e
+      rescue LoadError => e
         raise e unless e.is_missing? "helpers/#{module_path}_helper"
       rescue NameError => e
         raise e unless e.missing_name? "#{module_name}Helper"