diff --git a/src/ol/source/clustersource.js b/src/ol/source/clustersource.js
index 3e412fa349..17bdb8ac46 100644
--- a/src/ol/source/clustersource.js
+++ b/src/ol/source/clustersource.js
@@ -59,6 +59,15 @@ ol.source.Cluster = function(options) {
 goog.inherits(ol.source.Cluster, ol.source.Vector);
 
 
+/**
+ * @return {ol.source.Vector} Source.
+ * @api
+ */
+ol.source.Cluster.prototype.getSource = function() {
+  return this.source_;
+};
+
+
 /**
  * @inheritDoc
  */