diff --git a/pcbnew/router/pns_node.cpp b/pcbnew/router/pns_node.cpp
index 691a3d4d90..154376af90 100644
--- a/pcbnew/router/pns_node.cpp
+++ b/pcbnew/router/pns_node.cpp
@@ -1051,6 +1051,10 @@ const LINE NODE::AssembleLine( LINKED_ITEM* aSeg, int* aOriginSegmentIndex,
     // Remove duplicate verts, but do NOT remove colinear segments here!
     pl.Line().Simplify( false );
 
+    // TODO: maintain actual segment index under simplifcation system
+    if( aOriginSegmentIndex && *aOriginSegmentIndex >= pl.SegmentCount() )
+        *aOriginSegmentIndex = pl.SegmentCount() - 1;
+
     assert( pl.SegmentCount() != 0 );
 
     return pl;