diff --git a/include/asm-i386/tsc.h b/include/asm-i386/tsc.h
index 62c091f..a4d8066 100644
--- a/include/asm-i386/tsc.h
+++ b/include/asm-i386/tsc.h
@@ -63,6 +63,7 @@
 extern void mark_tsc_unstable(char *reason);
 extern int unsynchronized_tsc(void);
 extern void init_tsc_clocksource(void);
+int check_tsc_unstable(void);
 
 /*
  * Boot-time check whether the TSCs are synchronized across