diff --git a/src/Mod/CAM/Path/Op/SurfaceSupport.py b/src/Mod/CAM/Path/Op/SurfaceSupport.py
index e2aa7e451e..2323f416a7 100644
--- a/src/Mod/CAM/Path/Op/SurfaceSupport.py
+++ b/src/Mod/CAM/Path/Op/SurfaceSupport.py
@@ -2627,7 +2627,7 @@ class OCL_Tool:
             return
         self.oclTool = self.ocl.BullCutter(
             self.diameter,
-            self.diameter - self.flatRadius,
+            self.diameter / 2 - self.flatRadius,
             self.cutEdgeHeight + self.lengthOffset,
         )