diff --git a/gltf2tok3.py b/gltf2tok3.py
index b4a3696..e7a06d9 100755
--- a/gltf2tok3.py
+++ b/gltf2tok3.py
@@ -216,7 +216,7 @@ for input_filename in sys.argv[1:]:
 		
 		k3result["meshes"].append(mehs)
 	
-	if len(skin.joints) > 255:
+	if skin and len(skin.joints) > 255:
 		err("Bone maximum is 255")
 	
 	err_barrier()