diff --git a/EXE_GdbModifyCurve.cpp b/EXE_GdbModifyCurve.cpp
index df151c7..a8e228d 100644
--- a/EXE_GdbModifyCurve.cpp
+++ b/EXE_GdbModifyCurve.cpp
@@ -547,7 +547,8 @@ ExeSpiralizeCurveAlongGuide( int nCrvId, int nGuideId, double dLinTol)
       vtNext.Normalize() ;
       vSharpCorner1[i] = ( vtPrev * vtNext < CORNER_COS) ;
    }
-   vSharpCorner1.back() = vSharpCorner1.front() ;
+   if ( bOk)
+      vSharpCorner1.back() = vSharpCorner1.front() ;
 
    for ( int i = 0 ; i < nTotP2 - 1 ; i ++) {
       if ( i == 0  &&  ! PL2.IsClosed())
@@ -560,7 +561,8 @@ ExeSpiralizeCurveAlongGuide( int nCrvId, int nGuideId, double dLinTol)
       vtNext.Normalize() ;
       vSharpCorner2[i] = ( vtPrev * vtNext < CORNER_COS) ;
    }
-   vSharpCorner2.back() = vSharpCorner2.front() ;
+   if ( bOk)
+      vSharpCorner2.back() = vSharpCorner2.front() ;
 
   // se spigolo non associato ad altro spigolo, verifico se esiste un possibile spigolo da associare 
    for ( int i = 0 ; i < nTotP1 ; i ++) {
@@ -572,12 +574,17 @@ ExeSpiralizeCurveAlongGuide( int nCrvId, int nGuideId, double dLinTol)
          int nNextJ = vPnt1[nNextI].second ;
          int nStart = ( vSharpCorner2[nPrevJ] ? nPrevJ + 1 : nPrevJ) ;
          int nEnd = ( vSharpCorner2[nNextJ] ? nNextJ - 1 : nNextJ) ;
-         double dMinDist = INFINITO ;
+         double dSqMinDist = INFINITO ;
          int nCorner = vPnt1[i].second ;
         // cerco lo spigolo più vicino nel range fissato
-         for ( int j = nStart ; j <= nEnd ; j ++) {
-            if ( vSharpCorner2[j]  &&  Dist( vPnt1[i].first, vPnt2[j].first) < dMinDist)
-               nCorner = j ;
+         for ( int j = nStart ; j <= nEnd ; j ++) {             
+            if ( vSharpCorner2[j]) {
+               double dSqDist = SqDist( vPnt1[i].first, vPnt2[j].first) ;
+               if ( dSqDist < dSqMinDist) {
+                  dSqMinDist = dSqDist ;
+                  nCorner = j ;
+               }               
+            }               
          }
          vPnt1[i].second = nCorner ;
       }  
@@ -1005,7 +1012,7 @@ MyTrimCurveWithRegion( int nCrvId, int nRegId, bool bInVsOut, bool bOn, int& nCo
   // calcolo la classificazione della curva rispetto alla regione
    CRVCVECTOR ccClass ;
    if ( ! pSFR->GetCurveClassification( *CrvLoc, EPS_SMALL, ccClass))
-      return GDB_ID_NULL ;
+      return GDB_ID_NULL ;      
   // determino gli intervalli di curva da conservare
    Intervals inOk( 100 * EPS_PARAM) ;
    for ( auto& ccOne : ccClass) {