diff --git a/xs/xsp/Layer.xsp b/xs/xsp/Layer.xsp
index 3a20f3a02..469778f04 100644
--- a/xs/xsp/Layer.xsp
+++ b/xs/xsp/Layer.xsp
@@ -30,7 +30,6 @@
     
     Clone<Flow> flow(FlowRole role, bool bridge = false, double width = -1)
         %code%{ RETVAL = THIS->flow(role, bridge, width); %};
-    void merge_slices();
     void prepare_fill_surfaces();
     void make_perimeters(SurfaceCollection* slices, SurfaceCollection* fill_surfaces)
         %code%{ THIS->make_perimeters(*slices, fill_surfaces); %};