diff --git a/multi_user/bl_types/bl_mesh.py b/multi_user/bl_types/bl_mesh.py
index 8451eda..765a0a1 100644
--- a/multi_user/bl_types/bl_mesh.py
+++ b/multi_user/bl_types/bl_mesh.py
@@ -165,7 +165,8 @@ class BlMesh(BlDatablock):
         deps = []
         
         for material in self.pointer.materials:
-            deps.append(material)
+            if material:
+                deps.append(material)
         
         return deps