diff --git a/SurfRoughing.cpp b/SurfRoughing.cpp
index 8370081..1357e77 100644
--- a/SurfRoughing.cpp
+++ b/SurfRoughing.cpp
@@ -1365,7 +1365,7 @@ SurfRoughing::ProcessPath( int nPathId, int nTempId, int nPvId, int nClId)
          if ( abs( vExtraStep[i].second - vStepInfo[nIndRef].dDepth) < STEP_TOL) {
             for ( int j = i - 1 ; j >= nIndPrev ; -- j) {
                int nMyInd = ( j == i - 1 ? nIndRef : int( vStepInfo.size()) - 1) ;
-               bool bSS = ( vExtraStep[i].first == -1) ;
+               bool bSS = ( vExtraStep[j].first == -1) ;
                vStepInfo.emplace_back( nMyInd, vExtraStep[j].second, bSS, ! bSS,
                                        -1. , nullptr, nullptr) ;
                if ( ! bSS)