diff --git a/common/lib/xmodule/xmodule/open_ended_grading_classes/grading_service_module.py b/common/lib/xmodule/xmodule/open_ended_grading_classes/grading_service_module.py
index 3a107d51c1..6248c63091 100644
--- a/common/lib/xmodule/xmodule/open_ended_grading_classes/grading_service_module.py
+++ b/common/lib/xmodule/xmodule/open_ended_grading_classes/grading_service_module.py
@@ -42,7 +42,7 @@ class GradingService(object):
 
         response.raise_for_status()
 
-        return response.json
+        return response.json()
 
     def post(self, url, data, allow_redirects=False):
         """
@@ -88,9 +88,10 @@ class GradingService(object):
         Returns the result of operation().  Does not catch exceptions.
         """
         response = operation()
-        if (response.json
-            and response.json.get('success') is False
-            and response.json.get('error') == 'login_required'):
+        resp_json = response.json()
+        if (resp_json
+                and resp_json.get('success') is False
+                and resp_json.get('error') == 'login_required'):
             # apparrently we aren't logged in.  Try to fix that.
             r = self._login()
             if r and not r.get('success'):