diff --git a/CurveComposite.cpp b/CurveComposite.cpp
index b1a7f09..6419aba 100644
--- a/CurveComposite.cpp
+++ b/CurveComposite.cpp
@@ -209,8 +209,15 @@ CurveComposite::AddSimpleCurve( ICurve* pSmplCrv, bool bEndOrStart, double dLinT
          if ( ! AreSamePointEpsilon( ptCrvStart, ptEnd, 0.01 * EPS_SMALL)) {
            // se in tolleranza, modifico l'inizio dell'entità
             if ( SqDist( ptCrvStart, ptEnd) < ( dLinTol * dLinTol)) {
+              // lunghezza della curva originale
+               double dOldLen ; pCrv->GetLength( dOldLen) ;
+              // eseguo modifica
                if ( ! pCrv->ModifyStart( ptEnd))
                   return false ;
+              // verifico che la lunghezza non sia variata troppo
+               double dNewLen ; pCrv->GetLength( dNewLen) ;
+               if ( abs( dNewLen - dOldLen) > 10 * dLinTol)
+                  return false ;
             }
             else
                return false ;
diff --git a/EgtGeomKernel.rc b/EgtGeomKernel.rc
index f08cb69..80e1d54 100644
Binary files a/EgtGeomKernel.rc and b/EgtGeomKernel.rc differ
diff --git a/OffsetCurve.cpp b/OffsetCurve.cpp
index a7e989c..f91b2eb 100644
--- a/OffsetCurve.cpp
+++ b/OffsetCurve.cpp
@@ -589,16 +589,18 @@ OffsetCurve::Make( const ICurve* pCrv, double dDist, int nType)
          pCrvCo2->GetEndPoint( ptEnd2) ;
         // verifiche di concatenamento
          if ( AreSamePointEpsilon( ptEnd, ptStart2, 10 * EPS_SMALL)) {
-            pCrvCo->AddCurve( pCrvCo2, true, 10 * EPS_SMALL) ;
-            m_CrvLst.erase( iIter2) ;
-            ptEnd = ptEnd2 ;
-            iIter2 = next( iIter) ;
+            if ( pCrvCo->AddCurve( pCrvCo2, true, 10 * EPS_SMALL)) {
+               m_CrvLst.erase( iIter2) ;
+               ptEnd = ptEnd2 ;
+               iIter2 = next( iIter) ;
+            }
          }
          else if ( AreSamePointEpsilon( ptEnd2, ptStart, 10 * EPS_SMALL)) {
-            pCrvCo->AddCurve( pCrvCo2, false, 10 * EPS_SMALL) ;
-            m_CrvLst.erase( iIter2) ;
-            ptStart = ptStart2 ;
-            iIter2 = next( iIter) ;
+            if ( pCrvCo->AddCurve( pCrvCo2, false, 10 * EPS_SMALL)) {
+               m_CrvLst.erase( iIter2) ;
+               ptStart = ptStart2 ;
+               iIter2 = next( iIter) ;
+            }
          }
          else
             ++ iIter2 ;