diff --git a/CurveComposite.cpp b/CurveComposite.cpp
index 51abec2..d2fbc95 100644
--- a/CurveComposite.cpp
+++ b/CurveComposite.cpp
@@ -889,14 +889,21 @@ CurveComposite::Validate( void)
 
 //----------------------------------------------------------------------------
 bool
-CurveComposite::TestClosure( void)
+CurveComposite::TestClosure( double dLinTol)
 {
-  // se non è chiusa, esco subito
-   if ( ! IsClosed())
+  // se non valida o vuota, esco subito
+   if ( m_nStatus != OK  ||  m_CrvSmplS.empty())
+      return true ;
+  // se non è chiusa entro la tolleranza, esco subito
+   Point3d ptStart, ptEnd ;
+   if ( ! m_CrvSmplS.front()->GetStartPoint( ptStart)  ||
+        ! m_CrvSmplS.back()->GetEndPoint( ptEnd)  ||
+        ! AreSamePointEpsilon( ptStart, ptEnd, dLinTol))
+      return true ;
+  // se singola retta, esco subito
+   if ( m_CrvSmplS.size() == 1  &&  m_CrvSmplS.front()->GetType() == CRV_LINE)
       return true ;
   // verifico ed eventualmente aggiusto coincidenza punti estremi
-   Point3d ptStart ; m_CrvSmplS.front()->GetStartPoint( ptStart) ;
-   Point3d ptEnd ; m_CrvSmplS.back()->GetEndPoint( ptEnd) ;
    // se distanza superiore al limite ridotto forzo i punti a coincidere
    if ( ! AreSamePointEpsilon( ptStart, ptEnd, EPS_CONNECT)) {
      // se un solo arco
diff --git a/CurveComposite.h b/CurveComposite.h
index cc07fdf..f202bd4 100644
--- a/CurveComposite.h
+++ b/CurveComposite.h
@@ -198,13 +198,13 @@ class CurveComposite : public ICurveComposite, public IGeoObjRW
                        return *this ; }
       bool RelocateFrom( CurveComposite& ccSrc) ;
       bool GetApproxLength( double& dLen) const ;
+      bool TestClosure( double dLinTol = EPS_SMALL) ;
       Voronoi* GetVoronoiObject( void) const ;
       void ResetVoronoiObject( void) const ;
 
    private :
       bool CopyFrom( const CurveComposite& ccSrc) ;
       bool Validate( void) ;
-      bool TestClosure( void) ;
       bool AddCurveByRelocate( CurveComposite& ccSrc, bool bEndOrStart = true, double dLinTol = EPS_SMALL) ;
       bool AddSimpleCurve( ICurve* pSmplCrv, bool bEndOrStart = true, double dLinTol = EPS_SMALL) ;
       bool GetIndSCurveAndLocPar( double dU, Side nS, int& nSCrv, double& dLocU) const ;
diff --git a/VolZmapCalculus.cpp b/VolZmapCalculus.cpp
index 178f2ae..bb57461 100644
--- a/VolZmapCalculus.cpp
+++ b/VolZmapCalculus.cpp
@@ -3177,6 +3177,7 @@ VolZmap::GetPlaneIntersection( const Plane3d& plPlane, ICURVEPOVECTOR& vpLoop) c
          if ( ! pLoop->AddCurve( vLine[i - 1], true, 10 * EPS_SMALL))
             return false ;
       }
+      pLoop->TestClosure( 10 * EPS_SMALL) ;
       pLoop->SetExtrusion( plPlane.GetVersN()) ;
       pLoop->MergeCurves( 10 * EPS_SMALL, ANG_TOL_STD_DEG) ;
       // Inserisco la curva composita nella raccolta da ritornare