diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c
index fb413d3d8618..3a119a87686a 100644
--- a/fs/ntfs/file.c
+++ b/fs/ntfs/file.c
@@ -248,7 +248,7 @@ static int ntfs_attr_extend_initialized(ntfs_inode *ni, const s64 new_init_size,
 		 * enough to make ntfs_writepage() work.
 		 */
 		write_lock_irqsave(&ni->size_lock, flags);
-		ni->initialized_size = (index + 1) << PAGE_CACHE_SHIFT;
+		ni->initialized_size = (s64)(index + 1) << PAGE_CACHE_SHIFT;
 		if (ni->initialized_size > new_init_size)
 			ni->initialized_size = new_init_size;
 		write_unlock_irqrestore(&ni->size_lock, flags);