diff --git a/common/djangoapps/util/milestones_helpers.py b/common/djangoapps/util/milestones_helpers.py
index b4ec501a75..c7daaf277e 100644
--- a/common/djangoapps/util/milestones_helpers.py
+++ b/common/djangoapps/util/milestones_helpers.py
@@ -405,6 +405,7 @@ def any_unfulfilled_milestones(course_id, user_id):
     if not settings.FEATURES.get('MILESTONES_APP'):
         return False
 
+    user_id = None if user_id is None else int(user_id)
     fulfillment_paths = milestones_api.get_course_milestones_fulfillment_paths(course_id, {'id': user_id})
 
     # Returns True if any of the milestones is unfulfilled. False if