diff --git a/remotefilelog/lz4wrapper.py b/remotefilelog/lz4wrapper.py
--- a/remotefilelog/lz4wrapper.py
+++ b/remotefilelog/lz4wrapper.py
@@ -1,8 +1,15 @@
 from mercurial import error
 from mercurial.i18n import _
 
-from mercurial import demandimport
-demandimport.ignore.extend(['pkgutil', 'pkg_resources', '__main__'])
+from mercurial import (
+    demandimport,
+    util
+)
+if util.safehasattr(demandimport, 'IGNORES'):
+    # Since 670eb4fa1b86
+    demandimport.IGNORES.update(['pkgutil', 'pkg_resources', '__main__'])
+else:
+    demandimport.ignore.extend(['pkgutil', 'pkg_resources', '__main__'])
 
 def missing(*args, **kwargs):
     raise error.Abort(_('remotefilelog extension requires lz4 support'))