diff --git a/module/zfs/vdev_queue.c b/module/zfs/vdev_queue.c
index e828ce9176f5..19f67660fd39 100644
--- a/module/zfs/vdev_queue.c
+++ b/module/zfs/vdev_queue.c
@@ -606,6 +606,10 @@ vdev_queue_aggregate(vdev_queue_t *vq, zio_t *zio)
 	size = IO_SPAN(first, last);
 	ASSERT3U(size, <=, limit);
 
+	buf = zio_buf_alloc_flags(size, KM_NOSLEEP);
+	if (buf == NULL)
+		return (NULL);
+
 	buf = zio_buf_alloc_flags(size, KM_NOSLEEP);
 	if (buf == NULL)
 		return (NULL);