diff --git a/sbysrc/sby_core.py b/sbysrc/sby_core.py
index b0698d2..7d8cf0f 100644
--- a/sbysrc/sby_core.py
+++ b/sbysrc/sby_core.py
@@ -419,6 +419,8 @@ class SbyJob:
                 print("opt -fast", file=f)
                 print("abc -g AND -fast", file=f)
                 print("opt_clean", file=f)
+                print("setundef -anyseq", file=f)
+                print("opt_clean", file=f)
                 print("stat", file=f)
                 print("write_aiger -I -B -zinit -map design_aiger.aim design_aiger.aig", file=f)