diff --git a/space_view3d_copy_attributes.py b/space_view3d_copy_attributes.py
index 4a15939813da1ba09d50c0898d6514f1a72d5f40..19eb593f7fdca6c77482bea6ca0dbfc5fa7d7eb3 100644
--- a/space_view3d_copy_attributes.py
+++ b/space_view3d_copy_attributes.py
@@ -418,7 +418,7 @@ def obWei(ob, active, context):
                         groups = ob.vertex_groups
                         for vgs in range(0, len(groups)):
                             if groups[vgs].name == groupName:
-                                ob.vertex_groups.assign((v.index,), groups[vgs],
+                                groups[vgs].add((v.index,),
                                    vgroupIndex_weight[i][1], "REPLACE")
     return('INFO', "weights copied")