diff --git a/src/Mod/OpenSCAD/OpenSCADFeatures.py b/src/Mod/OpenSCAD/OpenSCADFeatures.py
index c62bd896a1..dc3cd8ad76 100644
--- a/src/Mod/OpenSCAD/OpenSCADFeatures.py
+++ b/src/Mod/OpenSCAD/OpenSCADFeatures.py
@@ -443,7 +443,7 @@ class Twist:
                     print(pipe_shell.getStatus())
                     assert(pipe_shell.isReady())
                     pipe_shell.build()
-                    faces.extend(pipeshell.shape().Faces)
+                    faces.extend(pipe_shell.shape().Faces)
                 try:
                     fullshell=Part.Shell(faces)
                     solid=Part.Solid(fullshell)