diff --git a/src/ol/format/osmxmlformat.js b/src/ol/format/osmxmlformat.js
index 888b1daf52..80655c0cdc 100644
--- a/src/ol/format/osmxmlformat.js
+++ b/src/ol/format/osmxmlformat.js
@@ -209,6 +209,17 @@ ol.format.OSMXML.prototype.readFeaturesFromNode = function(node) {
 };
 
 
+/**
+ * Read the projection from an OSM source.
+ *
+ * @function
+ * @param {ArrayBuffer|Document|Node|Object|string} source Source.
+ * @return {ol.proj.Projection} Projection.
+ * @todo api
+ */
+ol.format.OSMXML.prototype.readProjection;
+
+
 /**
  * @inheritDoc
  */