diff --git a/src/Mod/OpenSCAD/OpenSCADFeatures.py b/src/Mod/OpenSCAD/OpenSCADFeatures.py
index f817cff4ec..16e91c8d44 100644
--- a/src/Mod/OpenSCAD/OpenSCADFeatures.py
+++ b/src/Mod/OpenSCAD/OpenSCADFeatures.py
@@ -340,7 +340,7 @@ class Frustum:
                 pts.append(pts[0])
                 shape = Part.makePolygon(pts)
                 face = Part.Face(shape)
-                if ir==1: #top face
+                if ir==0: #top face
                     face.reverse()
                 wires.append(shape)
                 faces.append(face)