diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 4ffe09b..ac98d29 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -12,6 +12,7 @@
 #define MSR_FS_BASE		0xc0000100 /* 64bit FS base */
 #define MSR_GS_BASE		0xc0000101 /* 64bit GS base */
 #define MSR_KERNEL_GS_BASE	0xc0000102 /* SwapGS GS shadow */
+#define MSR_TSC_AUX		0xc0000103 /* Auxiliary TSC */
 
 /* EFER bits: */
 #define _EFER_SCE		0  /* SYSCALL/SYSRET */