diff --git a/module/zfs/vdev_file.c b/module/zfs/vdev_file.c
index 8c22aa5316..f31389a6df 100644
--- a/module/zfs/vdev_file.c
+++ b/module/zfs/vdev_file.c
@@ -143,7 +143,7 @@ vdev_file_io_start(zio_t *zio)
 {
 	vdev_t *vd = zio->io_vd;
 	vdev_file_t *vf = vd->vdev_tsd;
-	ssize_t resid;
+	ssize_t resid = 0;
 
 	if (zio->io_type == ZIO_TYPE_IOCTL) {
 		/* XXPOLICY */