diff --git a/src/ol/geom/abstractcollection.js b/src/ol/geom/abstractcollection.js
index abb4621dab..eabe5972fd 100644
--- a/src/ol/geom/abstractcollection.js
+++ b/src/ol/geom/abstractcollection.js
@@ -1,5 +1,6 @@
 goog.provide('ol.geom.AbstractCollection');
 
+goog.require('ol.extent');
 goog.require('ol.geom.Geometry');