diff --git a/redun/scheduler.py b/redun/scheduler.py
index b7dc063..8d13e97 100644
--- a/redun/scheduler.py
+++ b/redun/scheduler.py
@@ -1313,7 +1313,7 @@ def _add_job_pending_limits(self, job: Job, eval_args: Tuple[Tuple, dict]) -> No
 
     def _add_limits(self, limits1, limits2):
         return {
-            limit_name: limits1[limit_name] + limits2[limit_name]
+            limit_name: limits1.get(limit_name, 0) + limits2.get(limit_name, 0)
             for limit_name in set(limits1) | set(limits2)
         }