diff --git a/include/linux/futex.h b/include/linux/futex.h
index 90048fb..586ab56 100644
--- a/include/linux/futex.h
+++ b/include/linux/futex.h
@@ -167,6 +167,7 @@
 #ifdef CONFIG_FUTEX
 extern void exit_robust_list(struct task_struct *curr);
 extern void exit_pi_state_list(struct task_struct *curr);
+extern int futex_cmpxchg_enabled;
 #else
 static inline void exit_robust_list(struct task_struct *curr)
 {