diff --git a/lib/OpenLayers/Control/MousePosition.js b/lib/OpenLayers/Control/MousePosition.js
index 861281892b..119b4d52ad 100644
--- a/lib/OpenLayers/Control/MousePosition.js
+++ b/lib/OpenLayers/Control/MousePosition.js
@@ -18,6 +18,7 @@ OpenLayers.Control.MousePosition = OpenLayers.Class(OpenLayers.Control, {
     
     /** 
      * APIProperty: prefix
+     * {String}
      */
     prefix: '',