Index: data.c
===================================================================
--- data.c	(revision 29726)
+++ data.c	(revision 29727)
@@ -421,7 +421,7 @@
 	PCB_ENDALL_LOOP;
 	PCB_POLY_ALL_LOOP(data);
 	{
-		pcb_poly_mirror(layer, polygon, y_offs, undoable);
+		pcb_poly_mirror(polygon, y_offs, undoable);
 	}
 	PCB_ENDALL_LOOP;