diff --git a/src/base/abc/abcFunc.c b/src/base/abc/abcFunc.c
index 6b73bdc5d..c1fcfce21 100644
--- a/src/base/abc/abcFunc.c
+++ b/src/base/abc/abcFunc.c
@@ -819,6 +819,7 @@ int Abc_NtkSopToAig( Abc_Ntk_t * pNtk )
 
     // start the functionality manager
     pMan = Hop_ManStart();
+    Hop_IthVar( pMan, Abc_NtkGetFaninMax(pNtk)-1 );
 
     // convert each node from SOP to BDD
     Abc_NtkForEachNode( pNtk, pNode, i )