diff --git a/src/meshlabplugins/filter_ao/filter_ao.cpp b/src/meshlabplugins/filter_ao/filter_ao.cpp
index 40493f99f..d20557e90 100644
--- a/src/meshlabplugins/filter_ao/filter_ao.cpp
+++ b/src/meshlabplugins/filter_ao/filter_ao.cpp
@@ -284,13 +284,16 @@ bool AmbientOcclusionPlugin::processGL(MeshModel &m, vector<Point3f> &posVect)
 		{
 			tri::UpdateColor<CMeshO>::FaceQualityGray(m.cm);
 			CMeshO::FaceIterator fi;
-			for(fi=m.cm.face.begin();fi!=m.cm.face.end();++fi) if(!(*fi).IsD()) 
+      for(fi=m.cm.face.begin();fi!=m.cm.face.end();++fi)
 					(*fi).Q()=(*fi).Q()/numViews;
 		} else {
 			tri::UpdateColor<CMeshO>::VertexQualityGray(m.cm);
 			CMeshO::VertexIterator vi;
-			for(vi=m.cm.vert.begin();vi!=m.cm.vert.end();++vi) if(!(*vi).IsD()) 
+      for(vi=m.cm.vert.begin();vi!=m.cm.vert.end();++vi)
+      {
 					(*vi).Q()=(*vi).Q()/numViews;
+          BN[vi].Normalize();
+      }
 		}
 	
 	Log(0,"Successfully calculated A.O. after %3.2f sec, %3.2f of which is due to initialization", ((float)tAll.elapsed()/1000.0f), ((float)tInitElapsed/1000.0f) );