diff --git a/os-win32.c b/os-win32.c
index b214e6a678..c971d928ab 100644
--- a/os-win32.c
+++ b/os-win32.c
@@ -140,7 +140,9 @@ void os_host_main_loop_wait(int *timeout)
         int err;
         WaitObjects *w = &wait_objects;
 
+        qemu_mutex_unlock_iothread();
         ret = WaitForMultipleObjects(w->num, w->events, FALSE, *timeout);
+        qemu_mutex_lock_iothread();
         if (WAIT_OBJECT_0 + 0 <= ret && ret <= WAIT_OBJECT_0 + w->num - 1) {
             if (w->func[ret - WAIT_OBJECT_0])
                 w->func[ret - WAIT_OBJECT_0](w->opaque[ret - WAIT_OBJECT_0]);