diff --git a/src/ol/pixel.js b/src/ol/pixel.js
index 40c8a11da8..32571a060f 100644
--- a/src/ol/pixel.js
+++ b/src/ol/pixel.js
@@ -2,6 +2,9 @@ goog.provide('ol.Pixel');
 
 
 /**
+ * An array with two elements, representing a pixel. The first element is the
+ * x-coordinate, the second the y-coordinate of the pixel.
  * @typedef {Array.<number>}
+ * @todo api
  */
 ol.Pixel;