diff --git a/src/BeSimple/SoapBundle/Converter/XopIncludeTypeConverter.php b/src/BeSimple/SoapBundle/Converter/XopIncludeTypeConverter.php
index b83e38d9..a5c00b9e 100644
--- a/src/BeSimple/SoapBundle/Converter/XopIncludeTypeConverter.php
+++ b/src/BeSimple/SoapBundle/Converter/XopIncludeTypeConverter.php
@@ -12,7 +12,7 @@
 
 use BeSimple\SoapBundle\Soap\SoapRequest;
 use BeSimple\SoapBundle\Soap\SoapResponse;
-use BeSimple\SoapBundle\Util\String;
+use BeSimple\SoapBundle\Util\String as StringHelper;
 use BeSimple\SoapCommon\Converter\TypeConverterInterface;
 
 /**
@@ -40,7 +40,7 @@ public function convertXmlToPhp(SoapRequest $request, $data)
 
         $ref = $include->getAttribute('href');
 
-        if (String::startsWith($ref, 'cid:')) {
+        if (StringHelper::startsWith($ref, 'cid:')) {
             $cid = urldecode(substr($ref, 4));
 
             return $request->getSoapAttachments()->get($cid)->getContent();