diff --git a/VERSION b/VERSION
index 8740e51..5409a56 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-1.5.160
+1.5.161
diff --git a/base/netgen.c b/base/netgen.c
index 2c9fc88..f2e3830 100644
--- a/base/netgen.c
+++ b/base/netgen.c
@@ -2470,7 +2470,8 @@ void CopyProperties(struct objlist *obj_to, struct objlist *obj_from)
       kvcur->value.ival = 0;
 
       obj_to->instance.props = kvcopy;
-      obj_to->model.class = strsave(obj_from->model.class);
+      if (obj_from->model.class)
+         obj_to->model.class = strsave(obj_from->model.class);
    }
 }