diff --git a/app/apps/permits/api_queries_decos_join.py b/app/apps/permits/api_queries_decos_join.py
index fe8f8b511..69ed05727 100644
--- a/app/apps/permits/api_queries_decos_join.py
+++ b/app/apps/permits/api_queries_decos_join.py
@@ -276,7 +276,7 @@ def update_date_valid_until_for_omzettingsvergunning(self, permits):
                 and item.get("details")
                 and item["details"].get("DATE_VALID_UNTIL")
             ):
-                item["details"]["DATE_VALID_UNTIL"] = None
+                del item["details"]["DATE_VALID_UNTIL"]
 
     def log_error_info(self, parent_key, folder, decos_join_conf_object):
         logger.error("DECOS JOIN parent key not found in config")