diff --git a/block/aio_task.c b/block/aio_task.c
index 88989fa248..9bd17ea2c1 100644
--- a/block/aio_task.c
+++ b/block/aio_task.c
@@ -98,6 +98,8 @@ AioTaskPool *coroutine_fn aio_task_pool_new(int max_busy_tasks)
 {
     AioTaskPool *pool = g_new0(AioTaskPool, 1);
 
+    assert(max_busy_tasks > 0);
+
     pool->main_co = qemu_coroutine_self();
     pool->max_busy_tasks = max_busy_tasks;