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