diff --git a/event_routing_backends/processors/tests/fixtures/current/edx.grades.problem.submitted.weighted_possible_null.json b/event_routing_backends/processors/tests/fixtures/current/edx.grades.problem.submitted.weighted_possible_null.json
new file mode 100644
index 00000000..596b5757
--- /dev/null
+++ b/event_routing_backends/processors/tests/fixtures/current/edx.grades.problem.submitted.weighted_possible_null.json
@@ -0,0 +1,32 @@
+{
+    "context": {
+        "accept_language": "en-US,en;q=0.9",
+        "agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.116 Safari/537.36",
+        "client_id": "667522224.1583394645",
+        "course_id": "course-v1:edX+DemoX+Demo_Course",
+        "course_user_tags": {},
+        "host": "localhost:18000",
+        "ip": "172.18.0.1",
+        "module": {
+            "display_name": "Checkboxes",
+            "usage_key": "block-v1:edX+DemoX+Demo_Course+type@problem+block@3fc5461f86764ad7bdbdf6cbdde61e66"
+        },
+        "org_id": "edX",
+        "path": "/courses/course-v1:edX+DemoX+Demo_Course/xblock/block-v1:edX+DemoX+Demo_Course+type@problem+block@3fc5461f86764ad7bdbdf6cbdde61e66/handler/xmodule_handler/problem_check",
+        "referer": "http://localhost:18000/courses/course-v1:edX+DemoX+Demo_Course/courseware/8b66dcd2d6134eda9355089ece4f39f6/ef37eb3cf1724e38b7f88a9ce85a4842/?activate_block_id=block-v1%3AedX%2BDemoX%2BDemo_Course%2Btype%40sequential%2Bblock%40ef37eb3cf1724e38b7f88a9ce85a4842",
+        "session": "993110e9c27848a545da74a74114158d",
+        "user_id": 3,
+        "username": "edx"
+    },
+    "data": {
+        "course_id": "course-v1:edX+DemoX+Demo_Course",
+        "event_transaction_id": "07adb7b7-db7e-4cfd-9d69-5474a4c5774c",
+        "event_transaction_type": "edx.grades.problem.submitted",
+        "problem_id": "block-v1:edX+DemoX+Demo_Course+type@problem+block@3fc5461f86764ad7bdbdf6cbdde61e66",
+        "user_id": "3",
+        "weighted_earned": 0,
+        "weighted_possible": null
+    },
+    "name": "edx.grades.problem.submitted",
+    "timestamp": "2020-07-15T05:59:29.700909+00:00"
+}
diff --git a/event_routing_backends/processors/xapi/event_transformers/problem_interaction_events.py b/event_routing_backends/processors/xapi/event_transformers/problem_interaction_events.py
index 122f3523..6536b70f 100644
--- a/event_routing_backends/processors/xapi/event_transformers/problem_interaction_events.py
+++ b/event_routing_backends/processors/xapi/event_transformers/problem_interaction_events.py
@@ -151,16 +151,19 @@ def get_result(self):
             `Result`
         """
         event_data = self.get_data('data')
-        if event_data['weighted_possible'] > 0:
-            scaled = event_data['weighted_earned']/event_data['weighted_possible']
+        weighted_possible = event_data['weighted_possible'] or 0
+        weighted_earned = event_data['weighted_earned'] or 0
+
+        if weighted_possible > 0:
+            scaled = weighted_earned/weighted_possible
         else:
             scaled = 0
         return Result(
-            success=event_data['weighted_earned'] >= event_data['weighted_possible'],
+            success=weighted_earned >= weighted_possible,
             score={
                 'min': 0,
-                'max': event_data['weighted_possible'],
-                'raw': event_data['weighted_earned'],
+                'max': weighted_possible,
+                'raw': weighted_earned,
                 'scaled': scaled
             }
         )