diff --git a/CADability/SphericalSurface.cs b/CADability/SphericalSurface.cs
index cc575a4e2..cca3a8404 100644
--- a/CADability/SphericalSurface.cs
+++ b/CADability/SphericalSurface.cs
@@ -516,7 +516,7 @@ public override void GetZMinMax(Projection p, double umin, double umax, double v
 		/// <returns></returns>
 		public override ISurface Clone()
 		{
-			return new SphericalSurface(toSphere);
+			return new SphericalSurface(toSphere, usedArea);
 		}
 		/// <summary>
 		/// Overrides <see cref="CADability.GeoObject.ISurfaceImpl.Modify (ModOp)"/>