diff --git a/drivers/md/dm-cache-policy.h b/drivers/md/dm-cache-policy.h
index 558bdfdabf5f2da39e5bef487dc5008a2399b659..33369ca9614f978ae0481e0d79677c980660f42d 100644
--- a/drivers/md/dm-cache-policy.h
+++ b/drivers/md/dm-cache-policy.h
@@ -130,8 +130,8 @@ struct dm_cache_policy {
 	 *
 	 * Must not block.
 	 *
-	 * Returns 1 iff in cache, 0 iff not, < 0 on error (-EWOULDBLOCK
-	 * would be typical).
+	 * Returns 0 if in cache, -ENOENT if not, < 0 for other errors
+	 * (-EWOULDBLOCK would be typical).
 	 */
 	int (*lookup)(struct dm_cache_policy *p, dm_oblock_t oblock, dm_cblock_t *cblock);