diff --git a/src/ol/geom/multipolygon.js b/src/ol/geom/multipolygon.js
index bf694bc460..659e1bf12f 100644
--- a/src/ol/geom/multipolygon.js
+++ b/src/ol/geom/multipolygon.js
@@ -2,6 +2,7 @@ goog.provide('ol.geom.MultiPolygon');
 
 goog.require('goog.array');
 goog.require('goog.asserts');
+goog.require('ol.array');
 goog.require('ol.extent');
 goog.require('ol.geom.GeometryType');
 goog.require('ol.geom.MultiPoint');
@@ -91,7 +92,7 @@ ol.geom.MultiPolygon.prototype.appendPolygon = function(polygon) {
     this.endss_.push();
   } else {
     var offset = this.flatCoordinates.length;
-    goog.array.extend(this.flatCoordinates, polygon.getFlatCoordinates());
+    ol.array.safeExtend(this.flatCoordinates, polygon.getFlatCoordinates());
     ends = polygon.getEnds().slice();
     var i, ii;
     for (i = 0, ii = ends.length; i < ii; ++i) {
@@ -373,7 +374,7 @@ ol.geom.MultiPolygon.prototype.setPolygons = function(polygons) {
     for (j = 0, jj = ends.length; j < jj; ++j) {
       ends[j] += offset;
     }
-    goog.array.extend(flatCoordinates, polygon.getFlatCoordinates());
+    ol.array.safeExtend(flatCoordinates, polygon.getFlatCoordinates());
     endss.push(ends);
   }
   this.setFlatCoordinates(layout, flatCoordinates, endss);