diff --git a/i386/include/mach/i386/thread_status.h b/i386/include/mach/i386/thread_status.h
index 3de22ff3..32e40686 100644
--- a/i386/include/mach/i386/thread_status.h
+++ b/i386/include/mach/i386/thread_status.h
@@ -57,6 +57,7 @@
 #define	i386_V86_ASSIST_STATE	4
 #define	i386_REGS_SEGS_STATE	5
 #define	i386_DEBUG_STATE	6
+#define	i386_FSGS_BASE_STATE	7
 
 /*
  * This structure is used for both
@@ -179,4 +180,11 @@ struct i386_debug_state {
 #define	i386_DEBUG_STATE_COUNT \
 	    (sizeof(struct i386_debug_state)/sizeof(unsigned int))
 
+struct i386_fsgs_base_state {
+	unsigned long fs_base;
+	unsigned long gs_base;
+};
+#define i386_FSGS_BASE_STATE_COUNT \
+	    (sizeof(struct i386_fsgs_base_state)/sizeof(unsigned int))
+
 #endif	/* _MACH_I386_THREAD_STATUS_H_ */