diff --git a/sysdep/unix/io.c b/sysdep/unix/io.c
index 5ec728af..867f005f 100644
--- a/sysdep/unix/io.c
+++ b/sysdep/unix/io.c
@@ -2071,6 +2071,7 @@ watchdog_stop(void)
 
 volatile int async_config_flag;		/* Asynchronous reconfiguration/dump scheduled */
 volatile int async_dump_flag;
+volatile int async_shutdown_flag;
 
 void
 io_init(void)