diff --git a/lib/Slic3r/GUI/Plater.pm b/lib/Slic3r/GUI/Plater.pm
index f943193cd..6d518eacc 100644
--- a/lib/Slic3r/GUI/Plater.pm
+++ b/lib/Slic3r/GUI/Plater.pm
@@ -1761,6 +1761,7 @@ sub transform {
     return if !defined $obj_idx;
     
     my $model_object = $self->{model}->objects->[$obj_idx];
+    my $model_instance = $model_object->instances->[0];
     
     # apply Z rotation before mirroring
     $model_object->transform_by_instance($model_instance, 1);