diff --git a/endpoints/exception.py b/endpoints/exception.py
index 098e9ba12..41b113748 100644
--- a/endpoints/exception.py
+++ b/endpoints/exception.py
@@ -34,6 +34,10 @@ ERROR_DESCRIPTION = {
 
 class ApiException(Exception):
   """
+  Represents an error in the application/problem+json format.
+
+  See: https://tools.ietf.org/html/rfc7807
+
    -  "type" (string) - A URI reference that identifies the
       problem type.
 
diff --git a/static/js/directives/ui/signup-form.js b/static/js/directives/ui/signup-form.js
index 03c81a293..9e4a34246 100644
--- a/static/js/directives/ui/signup-form.js
+++ b/static/js/directives/ui/signup-form.js
@@ -46,10 +46,10 @@ angular.module('quay').directive('signupForm', function () {
           UserService.load();
         }, function(result) {
           $scope.registering  = false;
-          UIService.showFormError('#signupButton', result, null, ApiService);
+          UIService.showFormError('#signupButton', result);
         });
       };
     }
   };
   return directiveDefinitionObject;
-});
\ No newline at end of file
+});