--- a/python/mozbuild/mozbuild/artifacts.py
+++ b/python/mozbuild/mozbuild/artifacts.py
@@ -819,21 +819,20 @@ class Artifacts(object):
                           'pushid': pushid,
                           'num': NUM_PUSHHEADS_TO_QUERY_PER_PARENT},
                          'Retrieving the last {num} pushheads starting with id {pushid} on {tree}')
                 candidate_pushheads.extend(pushhead_cache.pushid_range(tree, start, end))
 
         return candidate_pushheads
 
     def _get_hg_revisions_from_git(self):
-
-        # First commit is HEAD, next is HEAD~1, etc.
         rev_list = subprocess.check_output([
             self._git, 'rev-list', '--topo-order',
-            'HEAD~{num}..HEAD'.format(num=NUM_REVISIONS_TO_QUERY),
+            '--max-count={num}'.format(num=NUM_REVISIONS_TO_QUERY),
+            'HEAD',
         ])
 
         hg_hash_list = subprocess.check_output([
             self._git, 'cinnabar', 'git2hg'
         ] + rev_list.splitlines())
 
         zeroes = "0" * 40