diff --git a/Lib/distutils/command/build_ext.py b/Lib/distutils/command/build_ext.py

index 86a85c1..66bf0c2 100644

--- a/Lib/distutils/command/build_ext.py

+++ b/Lib/distutils/command/build_ext.py

@@ -455,7 +455,7 @@ class build_ext (Command):

                   ("in 'ext_modules' option (extension '%s'), " +

                    "'sources' must be present and must be " +

                    "a list of source filenames") % ext.name

-        sources = list(sources)

+        sources = sorted(sources)

         ext_path = self.get_ext_fullpath(ext.name)

         depends = sources + ext.depends

​