diff --git a/src/ol/format/wfs.js b/src/ol/format/wfs.js
index 892fbe7caa..5ad2431144 100644
--- a/src/ol/format/wfs.js
+++ b/src/ol/format/wfs.js
@@ -791,8 +791,7 @@ ol.format.WFS.GETFEATURE_SERIALIZERS_ = {
  */
 ol.format.WFS.writeFilter = function(filter) {
   var child = ol.xml.createElementNS(ol.format.WFS.OGCNS, 'Filter');
-  var objectStack = [];
-  ol.format.WFS.writeFilterCondition_(child, filter, objectStack);
+  ol.format.WFS.writeFilterCondition_(child, filter, []);
   return child;
 };
 
diff --git a/test/spec/ol/format/wfs.test.js b/test/spec/ol/format/wfs.test.js
index 843a2b1c5a..89b76fa652 100644
--- a/test/spec/ol/format/wfs.test.js
+++ b/test/spec/ol/format/wfs.test.js
@@ -1017,7 +1017,7 @@ describe('ol.format.WFS', function() {
   describe('when writing out a WFS Filter', function() {
     it('creates a filter', function() {
       var text =
-          '<Filter>' +
+          '<Filter xmlns="http://www.opengis.net/ogc">' +
           '  <And>' +
           '    <PropertyIsLike wildCard="*" singleChar="." escapeChar="!">' +
           '      <PropertyName>name</PropertyName>' +