diff --git a/Mesh_3/include/CGAL/Mesh_3/Refine_facets_manifold_base.h b/Mesh_3/include/CGAL/Mesh_3/Refine_facets_manifold_base.h
index f34761589ff..d47fc3b27d1 100644
--- a/Mesh_3/include/CGAL/Mesh_3/Refine_facets_manifold_base.h
+++ b/Mesh_3/include/CGAL/Mesh_3/Refine_facets_manifold_base.h
@@ -190,7 +190,7 @@ private:
     typename std::vector<Facet>::iterator fit = facets.begin();
     while(fit != facets.end() && !r_c3t3_.is_in_complex(*fit)) ++fit;
     CGAL_assertion(fit!=facets.end());
-    CGAL_assertion_code(std::size_t facet_counter = 1);
+    CGAL_assertion_code(int facet_counter = 1);
 
 #ifdef CGAL_MESHES_DEBUG_REFINEMENT_POINTS
     std::cerr << "  " << v->cached_number_of_incident_facets()