diff --git a/mercurial/ancestor.py b/mercurial/ancestor.py
index 2d64571d46..5d7878fba5 100644
--- a/mercurial/ancestor.py
+++ b/mercurial/ancestor.py
@@ -5,9 +5,12 @@
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
+from __future__ import absolute_import
+
 import collections
 import heapq
-from node import nullrev
+
+from .node import nullrev
 
 def commonancestorsheads(pfunc, *nodes):
     """Returns a set with the heads of all common ancestors of all nodes,