diff --git a/SurfTriMeshBooleans.cpp b/SurfTriMeshBooleans.cpp
index e4428bf..9b62d49 100644
--- a/SurfTriMeshBooleans.cpp
+++ b/SurfTriMeshBooleans.cpp
@@ -1060,10 +1060,12 @@ SurfTriMesh::RetriangulationForBooleanOperation( CHAINMAP& LoopLines, TRIA3DVECT
             if ( nChainSize1 == nSameSeg) {
                cvOpenChain.erase( cvOpenChain.begin() + nCh1) ;
                vnDegVec.erase( vnDegVec.begin() + nCh1) ;
+               -- nCh1 ;
             }
             else if ( nChainSize2 == nSameSeg) {
                cvOpenChain.erase( cvOpenChain.begin() + nCh2) ;
                vnDegVec.erase( vnDegVec.begin() + nCh2) ;
+               -- nCh2 ;
             }
          }
       }