diff --git a/oauth2_provider/views/mixins.py b/oauth2_provider/views/mixins.py
index 168d5f42d..919878a9f 100644
--- a/oauth2_provider/views/mixins.py
+++ b/oauth2_provider/views/mixins.py
@@ -155,9 +155,17 @@ def error_response(self, error, **kwargs):
         :param error: :attr:`OAuthToolkitError`
         """
         oauthlib_error = error.oauthlib_error
+
+        separator = '?'
+        try:
+            if '?' in oauthlib_error.redirect_uri:
+                separator = '&'
+        except:
+            pass
+
         error_response = {
             'error': oauthlib_error,
-            'url': "{0}?{1}".format(oauthlib_error.redirect_uri, oauthlib_error.urlencoded)
+            'url': "{0}{1}{2}".format(oauthlib_error.redirect_uri, separator, oauthlib_error.urlencoded)
         }
         error_response.update(kwargs)