diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 1d49694e6ae3..c5880329ae37 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -6174,7 +6174,7 @@ static void btrfs_calculate_inode_block_rsv_size(struct btrfs_fs_info *fs_info,
 	 *
 	 * This is overestimating in most cases.
 	 */
-	qgroup_rsv_size = outstanding_extents * fs_info->nodesize;
+	qgroup_rsv_size = (u64)outstanding_extents * fs_info->nodesize;
 
 	spin_lock(&block_rsv->lock);
 	block_rsv->size = reserve_size;