diff --git a/include/linux/ata.h b/include/linux/ata.h
index b4c85e2..700c5b9b 100644
--- a/include/linux/ata.h
+++ b/include/linux/ata.h
@@ -1025,8 +1025,8 @@
 
 static inline int lba_28_ok(u64 block, u32 n_block)
 {
-	/* check the ending block number */
-	return ((block + n_block) < ((u64)1 << 28)) && (n_block <= 256);
+	/* check the ending block number: must be LESS THAN 0x0fffffff */
+	return ((block + n_block) < ((1 << 28) - 1)) && (n_block <= 256);
 }
 
 static inline int lba_48_ok(u64 block, u32 n_block)