diff --git a/fs/affs/file.c b/fs/affs/file.c
index e87ede608f77..1a4f092f24ef 100644
--- a/fs/affs/file.c
+++ b/fs/affs/file.c
@@ -539,7 +539,7 @@ affs_extent_file_ofs(struct inode *inode, u32 newsize)
 		tmp = min(bsize - boff, newsize - size);
 		BUG_ON(boff + tmp > bsize || tmp > bsize);
 		memset(AFFS_DATA(bh) + boff, 0, tmp);
-		AFFS_DATA_HEAD(bh)->size = cpu_to_be32(be32_to_cpu(AFFS_DATA_HEAD(bh)->size) + tmp);
+		be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
 		affs_fix_checksum(sb, bh);
 		mark_buffer_dirty_inode(bh, inode);
 		size += tmp;
@@ -680,7 +680,7 @@ static int affs_write_end_ofs(struct file *file, struct address_space *mapping,
 		tmp = min(bsize - boff, to - from);
 		BUG_ON(boff + tmp > bsize || tmp > bsize);
 		memcpy(AFFS_DATA(bh) + boff, data + from, tmp);
-		AFFS_DATA_HEAD(bh)->size = cpu_to_be32(be32_to_cpu(AFFS_DATA_HEAD(bh)->size) + tmp);
+		be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
 		affs_fix_checksum(sb, bh);
 		mark_buffer_dirty_inode(bh, inode);
 		written += tmp;