diff --git a/src/BeSimple/SoapClient/SoapClientBuilder.php b/src/BeSimple/SoapClient/SoapClientBuilder.php
index 20e5dc0..a8d5e15 100644
--- a/src/BeSimple/SoapClient/SoapClientBuilder.php
+++ b/src/BeSimple/SoapClient/SoapClientBuilder.php
@@ -39,7 +39,12 @@ class SoapClientBuilder extends AbstractSoapBuilder
     {
         $this->validateOptions();
 
-        return new SoapClient($this->wsdl, $this->getSoapOptions() + $this->soapOptionAuthentication);
+        return new SoapClient($this->wsdl, $this->getSoapOptions());
+    }
+
+    public function getSoapOptions()
+    {
+        return parent::getSoapOptions() + $this->soapOptionAuthentication;
     }
 
     /**
@@ -80,7 +85,7 @@ class SoapClientBuilder extends AbstractSoapBuilder
         $this->soapOptionAuthentication = array(
             'authentication' => SOAP_AUTHENTICATION_BASIC,
             'login'          => $username,
-            'password'       => $password
+            'password'       => $password,
         );
 
         return $this;
@@ -89,14 +94,17 @@ class SoapClientBuilder extends AbstractSoapBuilder
     /**
      * @return SoapClientBuilder
      */
-    public function withDigestAuthentication($certificate, $password)
+    public function withDigestAuthentication($certificate, $passphrase = null)
     {
         $this->soapOptionAuthentication = array(
             'authentication' => SOAP_AUTHENTICATION_DIGEST,
             'local_cert'     => $certificate,
-            'passphrase'     => $password
         );
 
+        if ($passphrase) {
+            $this->soapOptionAuthentication['passphrase'] = $passphrase;
+        }
+
         return $this;
     }
 
diff --git a/tests/BeSimple/Tests/SoapClient/SoapClientBuilderTest.php b/tests/BeSimple/Tests/SoapClient/SoapClientBuilderTest.php
index 7ba11c2..d256a01 100644
--- a/tests/BeSimple/Tests/SoapClient/SoapClientBuilderTest.php
+++ b/tests/BeSimple/Tests/SoapClient/SoapClientBuilderTest.php
@@ -62,6 +62,20 @@ class SoapClientBuilderTest extends \PHPUnit_Framework_TestCase
         $this->assertEquals($this->mergeOptions(array('user_agent' => 'BeSimpleSoap Test')), $builder->getSoapOptions());
     }
 
+    public function testWithAuthentication()
+    {
+        $builder = $this->getSoapBuilder();
+
+        $builder->withDigestAuthentication(__DIR__.'/Fixtures/cert.pem', 'foobar');
+        $this->assertEquals($this->mergeOptions(array('authentication' => SOAP_AUTHENTICATION_DIGEST, 'local_cert' => __DIR__.'/Fixtures/cert.pem', 'passphrase' => 'foobar')), $builder->getSoapOptions());
+
+        $builder->withDigestAuthentication(__DIR__.'/Fixtures/cert.pem');
+        $this->assertEquals($this->mergeOptions(array('authentication' => SOAP_AUTHENTICATION_DIGEST, 'local_cert' => __DIR__.'/Fixtures/cert.pem')), $builder->getSoapOptions());
+
+        $builder->withBasicAuthentication('foo', 'bar');
+        $this->assertEquals($this->mergeOptions(array('authentication' => SOAP_AUTHENTICATION_BASIC, 'login' => 'foo', 'password' => 'bar')), $builder->getSoapOptions());
+    }
+
     public function testCreateWithDefaults()
     {
         $builder = SoapClientBuilder::createWithDefaults();