diff --git a/src/sampling/sampledSurface/isoSurface/isoSurface.C b/src/sampling/sampledSurface/isoSurface/isoSurface.C
index 63c245e8c87b4fc74d215d79f77daae41da94ef6..e3105b35a56410fe8c6c1ee73425ac45874fcb95 100644
--- a/src/sampling/sampledSurface/isoSurface/isoSurface.C
+++ b/src/sampling/sampledSurface/isoSurface/isoSurface.C
@@ -1077,7 +1077,7 @@ Foam::triSurface Foam::isoSurface::stitchTriPoints
             {
                 // There is no (higher numbered) duplicate triangle
                 label newTriI = newToOldTri.size();
-                newToOldTri.append(triI);
+                newToOldTri.append(triMap[triI]);
                 tris[newTriI] = tris[triI];
             }
         }