diff --git a/LuaLibs/CalcPaths.lua b/LuaLibs/CalcPaths.lua
index 41d1697..d3d884f 100644
--- a/LuaLibs/CalcPaths.lua
+++ b/LuaLibs/CalcPaths.lua
@@ -598,11 +598,13 @@ local function ComputeRibsOrientedOffset( nRibsGrp, dStrand)
             else
                nNewId = EgtOffsetCurveAdv( vIds[i], - dOffs + k * dStrand)
             end
-            EgtSetName( nNewId, sName)
-            EgtSetInfo( nNewId, KEY_TYPE, TYPE.RIB)
-            EgtSetInfo( nNewId, KEY_ORIGINAL_RIB, vIds[i])
-            EgtRelocateGlob( nNewId, nOffsGrp)
-            table.insert( vOffs, nNewId)
+            if nNewId then
+               EgtSetName( nNewId, sName)
+               EgtSetInfo( nNewId, KEY_TYPE, TYPE.RIB)
+               EgtSetInfo( nNewId, KEY_ORIGINAL_RIB, vIds[i])
+               EgtRelocateGlob( nNewId, nOffsGrp)
+               table.insert( vOffs, nNewId)
+            end
          end
       end