diff --git a/flake8/hooks.py b/flake8/hooks.py
index 690aeed..6473c55 100644
--- a/flake8/hooks.py
+++ b/flake8/hooks.py
@@ -3,6 +3,12 @@ from __future__ import with_statement
 import os
 import sys
 from subprocess import Popen, PIPE
+try:
+    # The 'demandimport' breaks pyflakes and flake8._pyflakes
+    from mercurial import demandimport
+    demandimport.disable()
+except ImportError:
+    pass
 try:
     from configparser import ConfigParser
 except ImportError:   # Python 2