diff --git a/apps/mtm/serializers.py b/apps/mtm/serializers.py
index c2ab5961..161bea6e 100644
--- a/apps/mtm/serializers.py
+++ b/apps/mtm/serializers.py
@@ -163,7 +163,7 @@ class RouteSerializer(CustomModelSerializer):
         source='material_out.type', read_only=True)
     material_out_is_hidden = serializers.BooleanField(
         source='material_out.is_hidden', read_only=True)
-    material_out_tracking = serializers.IntegerField(source='material_out.tracking')
+    material_out_tracking = serializers.IntegerField(source='material_out.tracking', required=False)
 
     class Meta:
         model = Route