diff --git a/lib/api.rb b/lib/api.rb
index 5cc78e5..6882615 100644
--- a/lib/api.rb
+++ b/lib/api.rb
@@ -3,6 +3,7 @@ Dir["#{Rails.root}/lib/api/*.rb"].each {|file| require file}
 module Gitlab
   class API < Grape::API
     format :json
+    error_format :json
     helpers APIHelpers
 
     mount Users
diff --git a/lib/api/helpers.rb b/lib/api/helpers.rb
index cd2e39b..424a17b 100644
--- a/lib/api/helpers.rb
+++ b/lib/api/helpers.rb
@@ -5,7 +5,7 @@ module Gitlab
     end
 
     def authenticate!
-      error!('401 Unauthorized', 401) unless current_user
+      error!({'message' => '401 Unauthorized'}, 401) unless current_user
     end
   end
 end
--
libgit2 0.21.2