--- a/build/checksums.py
+++ b/build/checksums.py
@@ -7,17 +7,17 @@ from __future__ import with_statement
 
 from optparse import OptionParser
 import hashlib
 import logging
 import os
 
 logger = logging.getLogger('checksums.py')
 
-def digest_file(filename, digest, chunk_size=1024):
+def digest_file(filename, digest, chunk_size=131072):
     '''Produce a checksum for the file specified by 'filename'.  'filename'
     is a string path to a file that is opened and read in this function.  The
     checksum algorithm is specified by 'digest' and is a valid OpenSSL
     algorithm.  If the digest used is not valid or Python's hashlib doesn't
     work, the None object will be returned instead.  The size of blocks
     that this function will read from the file object it opens based on
     'filename' can be specified by 'chunk_size', which defaults to 1K'''
     assert not os.path.isdir(filename), 'this function only works with files'