diff --git a/sys/boot/zfs/zfsimpl.c b/sys/boot/zfs/zfsimpl.c
index ff567a4..a2893bf 100644
--- a/sys/boot/zfs/zfsimpl.c
+++ b/sys/boot/zfs/zfsimpl.c
@@ -920,6 +920,11 @@ zio_read(spa_t *spa, const blkptr_t *bp, void *buf)
 		if (!dva->dva_word[0] && !dva->dva_word[1])
 			continue;
 
+		if (DVA_GET_GANG(dva)) {
+			printf("ZFS: i/o error - gang block unimplemented!\n");
+			continue;
+		}
+
 		vdevid = DVA_GET_VDEV(dva);
 		offset = DVA_GET_OFFSET(dva);
 		STAILQ_FOREACH(vdev, &spa->spa_vdevs, v_childlink)