diff --git a/mercurial/pycompat.py b/mercurial/pycompat.py
new file mode 100644
--- /dev/null
+++ b/mercurial/pycompat.py
@@ -0,0 +1,18 @@
+# pycompat.py - portability shim for python 3
+#
+# This software may be used and distributed according to the terms of the
+# GNU General Public License version 2 or any later version.
+
+"""Mercurial portability shim for python 3.
+
+This contains aliases to hide python version-specific details from the core.
+"""
+
+from __future__ import absolute_import
+
+try:
+    import Queue as _queue
+except ImportError:
+    import queue as _queue
+empty = _queue.Empty
+queue = _queue.Queue
diff --git a/mercurial/util.py b/mercurial/util.py
--- a/mercurial/util.py
+++ b/mercurial/util.py
@@ -43,8 +43,15 @@ from . import (
     i18n,
     osutil,
     parsers,
+    pycompat,
 )
 
+for attr in (
+    'empty',
+    'queue',
+):
+    globals()[attr] = getattr(pycompat, attr)
+
 if os.name == 'nt':
     from . import windows as platform
 else: