diff --git a/sys/kern/kern_physio.c b/sys/kern/kern_physio.c
index 34442f9c505d..d74df443ed34 100644
--- a/sys/kern/kern_physio.c
+++ b/sys/kern/kern_physio.c
@@ -311,7 +311,7 @@ physio(void (*strategy)(struct buf *), struct buf *obp, dev_t dev, int flags,
 				 * aligned, the block addresses are used to track
 				 * errors of finished requests.
 				 */
-				if (dbtob(bp->b_blkno) != uio->uio_offset) {
+				if (uio->uio_offset & (DEV_BSIZE - 1)) {
 					error = EINVAL;
 					goto done;
 				}