diff --git a/LuaLibs/WProcessFreeContour.lua b/LuaLibs/WProcessFreeContour.lua
index ceb9901..681fead 100644
--- a/LuaLibs/WProcessFreeContour.lua
+++ b/LuaLibs/WProcessFreeContour.lua
@@ -768,7 +768,10 @@ local function GetEdgeToMachineFromVector( nSurfId, nFacet, vtOrtho)
    local nEdgeIndMax = 0
    local dMaxComp = - GEO.INFINITO
    for i = 1, #EdgesEgt do
-      local vtN = -EdgesEgt[i].Norm
+      local vtN = EdgesEgt[i].Norm
+      if EdgesEgt[i].Open then
+         vtN = -vtN
+      end
       local dComp = vtN * vtOrtho
       if dComp > dMaxComp then
          nEdgeIndMax = i -1