diff --git a/CurveComposite.cpp b/CurveComposite.cpp
index d94b97a..46d3ce8 100644
--- a/CurveComposite.cpp
+++ b/CurveComposite.cpp
@@ -849,9 +849,9 @@ CurveComposite::IsFlat( Plane3d& plPlane, bool bUseExtrusion, double dToler) con
       return false ;
   // ciclo sulle curve semplici (aggiungo solo eventuali punti intermedi e finali)
    int nCount = 0 ;
-   for ( const ICurve* pCrv = GetFirstCurve() ;
+   for ( const ICurve* pCrv = GetCurve( nCount) ;
          pCrv != nullptr ;
-         pCrv = GetNextCurve(), ++ nCount) {
+         pCrv = GetCurve( ++ nCount)) {
       switch ( pCrv->GetType()) {
       case CRV_LINE :
         // punto finale