diff --git a/hgext/convert/hg.py b/hgext/convert/hg.py
--- a/hgext/convert/hg.py
+++ b/hgext/convert/hg.py
@@ -26,7 +26,7 @@ from mercurial import hg, util, context,
 from common import NoRepo, commit, converter_source, converter_sink
 
 import re
-sha1re = re.compile(r'\b[0-9a-f]{6,40}\b')
+sha1re = re.compile(r'\b[0-9a-f]{12,40}\b')
 
 class mercurial_sink(converter_sink):
     def __init__(self, ui, path):