diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
index f9009e4f9ffd..f89f07c9580e 100644
--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -3666,8 +3666,8 @@ void dbFinalizeBmap(struct inode *ipbmap)
 	 * system size is not a multiple of the group size).
 	 */
 	inactfree = (inactags && ag_rem) ?
-	    ((inactags - 1) << bmp->db_agl2size) + ag_rem
-	    : inactags << bmp->db_agl2size;
+	    (((s64)inactags - 1) << bmp->db_agl2size) + ag_rem
+	    : ((s64)inactags << bmp->db_agl2size);
 
 	/* determine how many free blocks are in the active
 	 * allocation groups plus the average number of free blocks