--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -210,7 +210,7 @@ class lazyparser(object):
end = end * self.s
blocksize = end - blockstart
else:
- blockstart = (i & ~(32)) * self.s
+ blockstart = (i & ~63) * self.s
blocksize = self.s * 64
end = blockstart + blocksize
while blockstart < end: