diff --git a/src/ol/format/wfs.js b/src/ol/format/wfs.js
index 5ad2431144..5b0b19c0a5 100644
--- a/src/ol/format/wfs.js
+++ b/src/ol/format/wfs.js
@@ -399,6 +399,25 @@ ol.format.WFS.writeOgcFidFilter_ = function(node, fid, objectStack) {
 };
 
 
+/**
+ * @param {string|undefined} featurePrefix The prefix of the feature.
+ * @param {string} featureType The type of the feature.
+ * @returns {string} The value of the typeName property.
+ * @private
+ */
+ol.format.WFS.getTypeName_ = function(featurePrefix, featureType) {
+  featurePrefix = featurePrefix ? featurePrefix :
+      ol.format.WFS.FEATURE_PREFIX;
+  var prefix = featurePrefix + ':';
+  // The featureType already contains the prefix.
+  if (featureType.indexOf(prefix) === 0) {
+    return featureType;
+  } else {
+    return prefix + featureType;
+  }
+};
+
+
 /**
  * @param {Node} node Node.
  * @param {ol.Feature} feature Feature.
@@ -410,10 +429,9 @@ ol.format.WFS.writeDelete_ = function(node, feature, objectStack) {
   ol.asserts.assert(feature.getId() !== undefined, 26); // Features must have an id set
   var featureType = context['featureType'];
   var featurePrefix = context['featurePrefix'];
-  featurePrefix = featurePrefix ? featurePrefix :
-      ol.format.WFS.FEATURE_PREFIX;
   var featureNS = context['featureNS'];
-  node.setAttribute('typeName', featurePrefix + ':' + featureType);
+  var typeName = ol.format.WFS.getTypeName_(featurePrefix, featureType);
+  node.setAttribute('typeName', typeName);
   ol.xml.setAttributeNS(node, ol.format.WFS.XMLNS, 'xmlns:' + featurePrefix,
       featureNS);
   var fid = feature.getId();
@@ -434,10 +452,9 @@ ol.format.WFS.writeUpdate_ = function(node, feature, objectStack) {
   ol.asserts.assert(feature.getId() !== undefined, 27); // Features must have an id set
   var featureType = context['featureType'];
   var featurePrefix = context['featurePrefix'];
-  featurePrefix = featurePrefix ? featurePrefix :
-      ol.format.WFS.FEATURE_PREFIX;
   var featureNS = context['featureNS'];
-  node.setAttribute('typeName', featurePrefix + ':' + featureType);
+  var typeName = ol.format.WFS.getTypeName_(featurePrefix, featureType);
+  node.setAttribute('typeName', typeName);
   ol.xml.setAttributeNS(node, ol.format.WFS.XMLNS, 'xmlns:' + featurePrefix,
       featureNS);
   var fid = feature.getId();
@@ -538,8 +555,14 @@ ol.format.WFS.writeQuery_ = function(node, featureType, objectStack) {
   var featureNS = context['featureNS'];
   var propertyNames = context['propertyNames'];
   var srsName = context['srsName'];
-  var prefix = featurePrefix ? featurePrefix + ':' : '';
-  node.setAttribute('typeName', prefix + featureType);
+  var typeName;
+  // If feature prefix is not defined, we must not use the default prefix.
+  if (featurePrefix) {
+    typeName = ol.format.WFS.getTypeName_(featurePrefix, featureType);
+  } else {
+    typeName = featureType;
+  }
+  node.setAttribute('typeName', typeName);
   if (srsName) {
     node.setAttribute('srsName', srsName);
   }
diff --git a/test/spec/ol/format/wfs.test.js b/test/spec/ol/format/wfs.test.js
index 89b76fa652..0d9fe3ebc5 100644
--- a/test/spec/ol/format/wfs.test.js
+++ b/test/spec/ol/format/wfs.test.js
@@ -839,6 +839,47 @@ describe('ol.format.WFS', function() {
     });
   });
 
+  describe('when writing out a Transaction request', function() {
+    var text;
+    before(function(done) {
+      afterLoadText('spec/ol/format/wfs/TransactionMulti.xml', function(xml) {
+        text = xml;
+        done();
+      });
+    });
+
+    it('do not add feature prefx twice', function() {
+      var format = new ol.format.WFS();
+      var insertFeature = new ol.Feature({
+        the_geom: new ol.geom.MultiPoint([[1, 2]]),
+        foo: 'bar',
+        nul: null
+      });
+      insertFeature.setGeometryName('the_geom');
+      var inserts = [insertFeature];
+      var updateFeature = new ol.Feature({
+        the_geom: new ol.geom.MultiPoint([[1, 2]]),
+        foo: 'bar',
+        // null value gets Property element with no Value
+        nul: null,
+        // undefined value means don't create a Property element
+        unwritten: undefined
+      });
+      updateFeature.setId('fid.42');
+      var updates = [updateFeature];
+
+      var deleteFeature = new ol.Feature();
+      deleteFeature.setId('fid.37');
+      var deletes = [deleteFeature];
+      var serialized = format.writeTransaction(inserts, updates, deletes, {
+        featureNS: 'http://www.openplans.org/topp',
+        featureType: 'topp:states',
+        featurePrefix: 'topp'
+      });
+      expect(serialized).to.xmleql(ol.xml.parse(text));
+    });
+  });
+
 
   describe('when writing out a GetFeature request', function() {
     var text;