diff --git a/config.mk b/config.mk
index eba98c3..1635264 100644
--- a/config.mk
+++ b/config.mk
@@ -10,6 +10,10 @@ MANPREFIX = $(PREFIX)/share/man
 X11INC = /usr/X11R6/include
 X11LIB = /usr/X11R6/lib
 
+# include X11 in Ubuntu
+# X11INC = /usr/include/X11R6
+# X11LIB = /usr/lib/X11R6
+
 PKG_CONFIG = pkg-config
 
 # includes and libs