diff --git a/include/common/hathreads.h b/include/common/hathreads.h
index 5c4ceca7c..274f9882b 100644
--- a/include/common/hathreads.h
+++ b/include/common/hathreads.h
@@ -260,7 +260,7 @@ void thread_exit_sync(void);
 int  thread_no_sync(void);
 int  thread_need_sync(void);
 
-extern unsigned long all_threads_mask;
+extern volatile unsigned long all_threads_mask;
 
 #define ha_sigmask(how, set, oldset)  pthread_sigmask(how, set, oldset)
 
diff --git a/src/hathreads.c b/src/hathreads.c
index 5db3c2197..a3bca7d02 100644
--- a/src/hathreads.c
+++ b/src/hathreads.c
@@ -31,7 +31,7 @@ void thread_sync_io_handler(int fd)
 static HA_SPINLOCK_T sync_lock;
 static int           threads_sync_pipe[2];
 static unsigned long threads_want_sync = 0;
-unsigned long all_threads_mask  = 0;
+volatile unsigned long all_threads_mask  = 0;
 
 #if defined(DEBUG_THREAD) || defined(DEBUG_FULL)
 struct lock_stat lock_stats[LOCK_LABELS];
@@ -106,7 +106,7 @@ static inline void thread_sync_barrier(volatile unsigned long *barrier)
 
 	HA_ATOMIC_CAS(barrier, &old, 0);
 	HA_ATOMIC_OR(barrier, tid_bit);
-	while (*barrier != all_threads_mask)
+	while ((*barrier & all_threads_mask) != all_threads_mask)
 		pl_cpu_relax();
 }