diff --git a/fs/ext3/balloc.c b/fs/ext3/balloc.c
index 5a2c198762f0..22161740ba29 100644
--- a/fs/ext3/balloc.c
+++ b/fs/ext3/balloc.c
@@ -730,7 +730,7 @@ find_next_usable_block(ext3_grpblk_t start, struct buffer_head *bh,
 		here = 0;
 
 	p = ((char *)bh->b_data) + (here >> 3);
-	r = memscan(p, 0, (maxblocks - here + 7) >> 3);
+	r = memscan(p, 0, ((maxblocks + 7) >> 3) - (here >> 3));
 	next = (r - ((char *)bh->b_data)) << 3;
 
 	if (next < maxblocks && next >= start && ext3_test_allocatable(next, bh))