diff --git a/vai_reg/symbiyosys.sby b/vai_reg/symbiyosys.sby
index 67f9153..03b5552 100644
--- a/vai_reg/symbiyosys.sby
+++ b/vai_reg/symbiyosys.sby
@@ -6,8 +6,8 @@ mode prove
 #mode cover
 
 [engines]
-smtbmc
-#abc pdr
+#smtbmc
+abc pdr
 
 [script]
 verific -vhdl vai_reg.vhd