diff --git a/vcg/complex/algorithms/polygon_support.h b/vcg/complex/algorithms/polygon_support.h
index dc08b2bb..b4d293f9 100644
--- a/vcg/complex/algorithms/polygon_support.h
+++ b/vcg/complex/algorithms/polygon_support.h
@@ -112,6 +112,7 @@ namespace tri {
 	**/
 	static void ImportFromTriMesh( PolyMeshType & pm,  TriMeshType & tm){
 
+         vcg::tri::UpdateFlags<TriMeshType>::FaceClearV(tm);
 		// the vertices are the same, simply import them
 		int cnt = 0;
 		typename TriMeshType ::ConstVertexIterator tvi;