diff -r a9c71d578a1c -r 008d37c4d783 setup.py
--- a/setup.py	Fri Aug 12 11:35:17 2016 +0900
+++ b/setup.py	Sat Aug 13 12:08:23 2016 +0900
@@ -621,7 +621,7 @@
     osutil_ldflags += ['-framework', 'ApplicationServices']
 
 extmodules = [
-    Extension('mercurial.base85', ['mercurial/base85.c'],
+    Extension('mercurial.cext.base85', ['mercurial/cext/base85.c'],
               include_dirs=common_include_dirs,
               depends=common_depends),
     Extension('mercurial.bdiff', ['mercurial/bdiff.c',