diff --git a/src/ol/geom/flat/interpolate.js b/src/ol/geom/flat/interpolate.js
index a802949024..64c8a7ee79 100644
--- a/src/ol/geom/flat/interpolate.js
+++ b/src/ol/geom/flat/interpolate.js
@@ -1,5 +1,6 @@
 goog.provide('ol.geom.flat.interpolate');
 
+goog.require('ol');
 goog.require('ol.array');
 goog.require('ol.math');