diff --git a/programs/winedbg/db_disasm64.c b/programs/winedbg/db_disasm64.c
index 4d4e2eb8c7b..d7f7c032a15 100644
--- a/programs/winedbg/db_disasm64.c
+++ b/programs/winedbg/db_disasm64.c
@@ -1495,11 +1495,11 @@ db_disasm(db_addr_t loc, boolean_t altfmt)
 		    break;
 
 		case S:
-		    db_printf("%s", db_seg_reg[f_reg(rex, regmodrm)]);
+		    db_printf("%s", db_seg_reg[f_reg(0, regmodrm)]);
 		    break;
 
 		case Si:
-		    db_printf("%s", db_seg_reg[f_reg(rex, inst)]);
+		    db_printf("%s", db_seg_reg[f_reg(0, inst)]);
 		    break;
 
 		case A: