diff --git a/lib/controllers/providers/api/gas_refill_provider.dart b/lib/controllers/providers/api/gas_refill_provider.dart
index 33c9fd61..e2401668 100644
--- a/lib/controllers/providers/api/gas_refill_provider.dart
+++ b/lib/controllers/providers/api/gas_refill_provider.dart
@@ -153,7 +153,7 @@ class GasRefillProvider extends ChangeNotifier {
       "endDate": endDate?.toIso8601String(),
       "endTime": endDate?.toIso8601String(),
       "workingHours": ((endDate?.difference(startDate)?.inMinutes ?? 0) / 60),
-      "assignedEmployee": oldModel?.assignedEmployee?.toJson(),
+      "assignedEmployee": oldModel?.assignedEmployee?.id == null ? null : oldModel?.assignedEmployee?.toJson(),
       "site": hospital?.toMap(),
       "building": building?.toJson(includeFloors: false),
       "floor": floor?.toJson(includeDepartments: false),