diff --git a/luaa.c b/luaa.c
index daa9be4b0..28b8aa3e6 100644
--- a/luaa.c
+++ b/luaa.c
@@ -20,12 +20,22 @@
  */
 
 /** awesome core API
+ *
+ * Additionally to the classes described here, one can also use X properties as
+ * described in @{xproperties}.
  *
  * @author Julien Danjou <julien@danjou.info>
  * @copyright 2008-2009 Julien Danjou
  * @module awesome
  */
 
+/** Register a new xproperty.
+ *
+ * @tparam string name The name of the X11 property.
+ * @tparam string type One of "string", "number" or "boolean".
+ * @function register_xproperty
+ */
+
 #define _GNU_SOURCE
 
 #include "luaa.h"