diff --git a/setup.py b/setup.py
index 779b2600d..238088655 100644
--- a/setup.py
+++ b/setup.py
@@ -114,7 +114,7 @@ class pil_build_ext(build_ext):
             _add_directory(include_dirs, "/opt/local/include")
             # freetype2 ships with X11
             _add_directory(library_dirs, "/usr/x11/lib")
-            _add_directory(library_dirs, "/usr/x11/include")
+            _add_directory(include_dirs, "/usr/x11/include")
 
         elif sys.platform == "linux2":
             if platform.processor() == "x86_64":