diff --git a/merb-core/lib/merb-core/controller/mixins/responder.rb b/merb-core/lib/merb-core/controller/mixins/responder.rb
index <HASH>..<HASH> 100644
--- a/merb-core/lib/merb-core/controller/mixins/responder.rb
+++ b/merb-core/lib/merb-core/controller/mixins/responder.rb
@@ -297,7 +297,7 @@ module Merb
     #
     # :api: private
     def _perform_content_negotiation
-      if fmt = params[:format]
+      if fmt = params[:format] and !fmt.blank?
         accepts = [fmt.to_sym]
       else
         accepts = _accept_types
[merb-core] Content negotiation handles blank formats like nil

Fixes specs to support the "get/post/put/delete"
test helpers properly.