diff --git a/setupext.py b/setupext.py
index 1198bd0ab854..5258c40e4338 100644
--- a/setupext.py
+++ b/setupext.py
@@ -289,7 +289,7 @@ def setup_extension(self, ext, package, default_include_dirs=[],
                 for token in output.split():
                     attr = flag_map.get(token[:2])
                     if attr is not None:
-                        getattr(ext, attr).append(token[2:])
+                        getattr(ext, attr).insert(0, token[2:])
 
         if use_defaults:
             basedirs = get_base_dirs()