diff --git a/graphicswin.cpp b/graphicswin.cpp
index 3c48e48..9f70f1b 100644
--- a/graphicswin.cpp
+++ b/graphicswin.cpp
@@ -1189,9 +1189,12 @@ void GraphicsWindow::Paint(int w, int h) {
         SBsp3 *pb = SBsp3::FromMesh(mb);
 
         SMesh br; ZERO(&br);
-        br.flipNormal = true; br.keepCoplanar = false;
+        br.flipNormal = true;
+        br.keepCoplanar = false;
         br.AddAgainstBsp(mb, pa);
-        br.flipNormal = false; br.keepCoplanar = false;
+
+        br.flipNormal = false;
+        br.keepCoplanar = false;
         br.AddAgainstBsp(ma, pb);
 
         dbp("triangles in = %d %d out = %d", ma->l.n, mb->l.n, br.l.n);
diff --git a/mesh.cpp b/mesh.cpp
index 8f69045..d92e671 100644
--- a/mesh.cpp
+++ b/mesh.cpp
@@ -104,10 +104,10 @@ void SBsp3::InsertInPlane(bool pos2, STriangle *tr, SMesh *m) {
         }
         ll = ll->more;
     }
-    
-    if(m->flipNormal && !pos2 && (!onFace || !sameNormal)) {
+
+    if(m->flipNormal && ((!pos2 && !onFace) || (onFace && !sameNormal))) {
         m->AddTriangle(tr->c, tr->b, tr->a);
-    } else if(!(m->flipNormal) && (pos2 || 
+    } else if(!(m->flipNormal) && ((pos2 && !onFace) || 
                                    (onFace && sameNormal && m->keepCoplanar)))
     {
         m->AddTriangle(tr->a, tr->b, tr->c);
@@ -153,6 +153,7 @@ alt:
         } else {
             // I suppose this actually is allowed to happen, if the coplanar
             // face is the leaf, and all of its neighbors are earlier in tree?
+            dbp("insert in plane");
             InsertInPlane(false, tr, instead);
         }
     } else {