diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 4cf2817ab120..f9e280d0b44f 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -275,7 +275,8 @@ static blk_status_t __btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio
 		csum += count * csum_size;
 		nblocks -= count;
 next:
-		while (count--) {
+		while (count > 0) {
+			count--;
 			disk_bytenr += fs_info->sectorsize;
 			offset += fs_info->sectorsize;
 			page_bytes_left -= fs_info->sectorsize;