diff --git a/SurfFlatRegion.cpp b/SurfFlatRegion.cpp
index 121b82f..6747bcb 100644
--- a/SurfFlatRegion.cpp
+++ b/SurfFlatRegion.cpp
@@ -1215,12 +1215,12 @@ SurfFlatRegion::CalcAuxSurf( double dLinTol, double dAngTolDeg) const
       ICurve* pLoop = GetMyLoop( i, j) ;
       while ( pLoop != nullptr) {
         // approssimo con linee a destra per non avere problemi in punti di contatto tra esterni e interni
-         PolyLine PL ;
-         if ( ! pLoop->ApproxWithLines( dLinTol, dAngTolDeg, ICurve::APL_RIGHT, PL))
+         vPL.emplace_back( PolyLine()) ;
+         if ( ! pLoop->ApproxWithLines( dLinTol, dAngTolDeg, ICurve::APL_RIGHT, vPL.back()))
             return nullptr ;
          double dLoopArea ;
-         if ( PL.GetAreaXY( dLoopArea)  &&  abs( dLoopArea) > 25 * SQ_EPS_SMALL)
-            vPL.emplace_back( PL) ;
+         if ( ! vPL.back().GetAreaXY( dLoopArea)  ||  abs( dLoopArea) <= 25 * SQ_EPS_SMALL)
+            vPL.pop_back() ;
          pLoop = GetMyLoop( i, ++j) ;
       }
      // se chunk abbastanza grande, creo la superficie trimesh relativa