diff --git a/src/haproxy.c b/src/haproxy.c
index 870dfd1..74fb70e 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -141,7 +141,8 @@
 unsigned long pid_bit = 1;      /* bit corresponding to the process id */
 unsigned long all_proc_mask = 1; /* mask of all processes */
 
-volatile unsigned long sleeping_thread_mask; /* Threads that are about to sleep in poll() */
+volatile unsigned long sleeping_thread_mask = 0; /* Threads that are about to sleep in poll() */
+
 /* global options */
 struct global global = {
 	.hard_stop_after = TICK_ETERNITY,