diff --git a/lib/Slic3r/Print.pm b/lib/Slic3r/Print.pm
index 90a1b010..65d166e7 100644
--- a/lib/Slic3r/Print.pm
+++ b/lib/Slic3r/Print.pm
@@ -972,7 +972,7 @@ sub write_gcode {
                     }
                     print $fh $buffer->append(
                         $layer_gcode->process_layer($layer, [$copy]),
-                        $layer->object."",
+                        $layer->object->ptr,
                         $layer->id,
                         $layer->print_z,
                     );
@@ -1005,7 +1005,7 @@ sub write_gcode {
                 foreach my $layer (@{ $layers{$print_z}[$obj_idx] // [] }) {
                     print $fh $buffer->append(
                         $layer_gcode->process_layer($layer, $layer->object->_shifted_copies),
-                        $layer->object . ref($layer),  # differentiate $obj_id between normal layers and support layers
+                        $layer->object->ptr . ref($layer),  # differentiate $obj_id between normal layers and support layers
                         $layer->id,
                         $layer->print_z,
                     );
diff --git a/xs/xsp/Layer.xsp b/xs/xsp/Layer.xsp
index de076767..6c5243ae 100644
--- a/xs/xsp/Layer.xsp
+++ b/xs/xsp/Layer.xsp
@@ -57,6 +57,9 @@
 
     Ref<ExPolygonCollection> slices()
         %code%{ RETVAL = &THIS->slices; %};
+    
+    int ptr()
+        %code%{ RETVAL = (int)(intptr_t)THIS; %};
 };
 
 %name{Slic3r::Layer::Support} class SupportLayer {