diff --git a/src/aig/gia/giaSpeedup.c b/src/aig/gia/giaSpeedup.c
index 0d5939935..b9f4f0371 100644
--- a/src/aig/gia/giaSpeedup.c
+++ b/src/aig/gia/giaSpeedup.c
@@ -246,6 +246,7 @@ float Gia_ManDelayTraceLut( Gia_Man_t * p )
 
     // initialize the arrival times
     Gia_ManTimeStart( p );
+    Gia_ManLevelNum( p );
 
     // propagate arrival times
     if ( p->pManTime )