diff --git a/CurveComposite.h b/CurveComposite.h
index 2028084..127d665 100644
--- a/CurveComposite.h
+++ b/CurveComposite.h
@@ -228,3 +228,16 @@ inline CurveComposite* GetBasicCurveComposite( IGeoObj* pGObj)
                { if ( pGObj == nullptr  ||  pGObj->GetType() != CRV_COMPO)
                     return nullptr ;
                  return ( static_cast<CurveComposite*>( pGObj)) ; }
+inline CurveComposite* ConvertCurveToBasicComposite( IGeoObj* pGObj)
+               { if ( pGObj == nullptr  ||  ( pGObj->GetType() & GEO_CURVE) == 0) {
+                    delete pGObj ;
+                    return nullptr ;
+                 }
+                 CurveComposite* pCrvCo = CreateBasicCurveComposite() ;
+                 if ( pCrvCo == nullptr) {
+                    delete pGObj ;
+                    return nullptr ;
+                 }
+                 pCrvCo->AddCurve( static_cast<ICurve*>( pGObj)) ;
+                 return pCrvCo ;
+               }
diff --git a/SfrCreate.cpp b/SfrCreate.cpp
index 6e4fb9d..00392cf 100644
--- a/SfrCreate.cpp
+++ b/SfrCreate.cpp
@@ -124,8 +124,8 @@ GetSurfFlatRegionFromFatCurve( ICurve* pCrv, double dRadius, bool bSquareEnds, b
    Vector3d vtExtr ; pCrv->GetExtrusion( vtExtr) ;
    if ( vtExtr.IsSmall())
       vtExtr = Z_AX ;
-   PtrOwner<CurveComposite> pCompo1( CreateBasicCurveComposite()) ;
-   if ( IsNull( pCompo1)  ||  ! pCompo1->AddCurve( Release( pCurve)))
+   PtrOwner<CurveComposite> pCompo1 ;
+   if ( ! pCompo1.Set( ConvertCurveToBasicComposite( Release( pCurve))))
       return nullptr ;
    pCompo1->SetExtrusion( vtExtr) ;
   // se distanza tra gli estremi minore di due volte il raggio la chiudo, purchè curva abbastanza lunga