diff --git a/src/ol/tile/tileurlfunction.js b/src/ol/tile/tileurlfunction.js
index 38ef5179b9..6e8c29c6c0 100644
--- a/src/ol/tile/tileurlfunction.js
+++ b/src/ol/tile/tileurlfunction.js
@@ -54,6 +54,15 @@ ol.TileUrlFunction.createFromTemplates = function(templates) {
 };
 
 
+/**
+ * @param {ol.TileCoord} tileCoord Tile coordinate.
+ * @return {string|undefined} Tile URL.
+ */
+ol.TileUrlFunction.nullTileUrlFunction = function(tileCoord) {
+  return undefined;
+};
+
+
 /**
  * @param {function(ol.TileCoord): ol.TileCoord} transform Transform.
  * @param {ol.TileUrlFunctionType} tileUrlFunction Tile URL function.