diff --git a/src/aig/gia/giaFx.c b/src/aig/gia/giaFx.c
index 032ae5fc4..c20241ed1 100644
--- a/src/aig/gia/giaFx.c
+++ b/src/aig/gia/giaFx.c
@@ -150,6 +150,13 @@ Vec_Wrd_t * Gia_ManComputeTruths( Gia_Man_t * p, int nCutSize, int nLutNum, int
         // collect and sort fanins
         vLeaves.nCap = vLeaves.nSize = Gia_ObjLutSize( p, i );
         vLeaves.pArray = Gia_ObjLutFanins( p, i );
+        if( !Vec_IntCheckUniqueSmall(&vLeaves) ) 
+        {
+            Vec_IntUniqify(&vLeaves);
+            Vec_IntWriteEntry(p->vMapping, Vec_IntEntry(p->vMapping, i), vLeaves.nSize);
+            for ( k = 0; k < vLeaves.nSize; k++ )
+                Vec_IntWriteEntry(p->vMapping, Vec_IntEntry(p->vMapping, i) + 1 + k, vLeaves.pArray[k]);
+        }
         assert( Vec_IntCheckUniqueSmall(&vLeaves) );
         Vec_IntSelectSort( Vec_IntArray(&vLeaves), Vec_IntSize(&vLeaves) );
         if ( !fReverse )