diff --git a/saturn_hp48gx_rom.v b/saturn_hp48gx_rom.v
index 480749c..a2e1390 100644
--- a/saturn_hp48gx_rom.v
+++ b/saturn_hp48gx_rom.v
@@ -23,7 +23,7 @@
 `ifdef SIM
 `define ROMBITS 20
 `else
-`define ROMBITS 12
+`define ROMBITS 13
 `endif
 
 `include "saturn_def_buscmd.v"