diff --git a/sys/x86/include/specialreg.h b/sys/x86/include/specialreg.h
index a8ff7aa2b30..87461bdeafe 100644
--- a/sys/x86/include/specialreg.h
+++ b/sys/x86/include/specialreg.h
@@ -54,6 +54,8 @@
 #define	CR0_CD  0x40000000	/* Cache Disable */
 
 #define	CR3_PCID_MASK	0x0000000000000fff
+#define	CR3_LAM_U57	0x2000000000000000
+#define	CR3_LAM_U48	0x4000000000000000
 #define	CR3_PCID_SAVE	0x8000000000000000
 
 /*