diff --git a/src/model_physics.rs b/src/model_physics.rs
index 7647672..65e8bad 100644
--- a/src/model_physics.rs
+++ b/src/model_physics.rs
@@ -556,14 +556,14 @@ impl MeshQuery<MinkowskiFace,MinkowskiDirectedEdge,MinkowskiVert> for MinkowskiM
 				let v1f=self.mesh1.vert_faces(v1);
 				for &directed_edge_id in self.mesh0.vert_edges(v0).iter(){
 					let n=self.mesh0.directed_edge_n(directed_edge_id);
-					if v1f.iter().any(|&face_id|n.dot(self.mesh1.face_nd(face_id).0)<Planar64::ZERO){
+					if v1f.iter().any(|&face_id|n.dot(self.mesh1.face_nd(face_id).0)<=Planar64::ZERO){
 						edges.push(MinkowskiDirectedEdge::EdgeVert(directed_edge_id,v1));
 					}
 				}
 				let v0f=self.mesh0.vert_faces(v0);
 				for &directed_edge_id in self.mesh1.vert_edges(v1).iter(){
 					let n=self.mesh1.directed_edge_n(directed_edge_id);
-					if v0f.iter().any(|&face_id|n.dot(self.mesh0.face_nd(face_id).0)<Planar64::ZERO){
+					if v0f.iter().any(|&face_id|n.dot(self.mesh0.face_nd(face_id).0)<=Planar64::ZERO){
 						edges.push(MinkowskiDirectedEdge::VertEdge(v0,directed_edge_id));
 					}
 				}