diff --git a/src/Mod/OpenSCAD/importCSG.py b/src/Mod/OpenSCAD/importCSG.py
index 6abb4d67aa..ba97697776 100644
--- a/src/Mod/OpenSCAD/importCSG.py
+++ b/src/Mod/OpenSCAD/importCSG.py
@@ -825,7 +825,7 @@ def p_cylinder_action(p):
             else: #Use Part::Prism primitive
                 mycyl=doc.addObject("Part::Prism","prism")
                 mycyl.Polygon = n
-                mycyl.Length  = r1
+                mycyl.Circumradius  = r1
                 mycyl.Height  = h
 
     else:
diff --git a/src/Mod/OpenSCAD/prototype.py b/src/Mod/OpenSCAD/prototype.py
index 65b42c09f7..86c49d6d70 100644
--- a/src/Mod/OpenSCAD/prototype.py
+++ b/src/Mod/OpenSCAD/prototype.py
@@ -136,7 +136,7 @@ class Node:
                 if r1 == r2: # prismatic
                     obj = doc.addObject("Part::Prism","prism")
                     obj.Polygon = int(self.arguments['$fn'])
-                    obj.Length  = r1
+                    obj.Circumradius  = r1
                     obj.Height  = h
                     if self.arguments['center']:
                         center(obj,0,0,h)