diff --git a/src/cpu/x86/smm/smm_stub.S b/src/cpu/x86/smm/smm_stub.S
index 11ea9a71a8..56e2504892 100644
--- a/src/cpu/x86/smm/smm_stub.S
+++ b/src/cpu/x86/smm/smm_stub.S
@@ -91,7 +91,7 @@ smm_relocate_gdt:
 
 	/* gdt selector 0x18, flat code segment (64-bit) */
 	.word	0xffff, 0x0000
-	.byte	0x00, 0x9b, 0xcf, 0x00
+	.byte	0x00, 0x9b, 0xaf, 0x00
 
 	/* gdt selector 0x20 tss segment */
 	.word   0xffff, 0x0000