diff --git a/apps/enm/views.py b/apps/enm/views.py
index a3fb1232..7f9e84c9 100644
--- a/apps/enm/views.py
+++ b/apps/enm/views.py
@@ -39,7 +39,7 @@ class MpointViewSet(CustomModelViewSet):
             "enabled": ["exact"],
             "need_display": ["exact"],
             "formula": ["exact", "contains"],
-            "material": ["exact"],
+            "material": ["exact", "isnull"],
             "material__code": ["exact", "in"],
             "code": ["exact", "contains", "in"],
         }