diff --git a/src/ol/format/filter/logicalnary.js b/src/ol/format/filter/logicalnary.js
index fd19fe8909..530c5e4d4f 100644
--- a/src/ol/format/filter/logicalnary.js
+++ b/src/ol/format/filter/logicalnary.js
@@ -1,6 +1,7 @@
 goog.provide('ol.format.filter.LogicalNary');
 
 goog.require('ol');
+goog.require('ol.asserts');
 goog.require('ol.format.filter.Filter');