diff --git a/src/XMLSerializer.php b/src/XMLSerializer.php
index 3f477b5..253509f 100644
--- a/src/XMLSerializer.php
+++ b/src/XMLSerializer.php
@@ -2,6 +2,7 @@
 namespace TheSeer\Tokenizer;
 
 use DOMDocument;
+use XMLWriter;
 
 class XMLSerializer {
 
@@ -32,7 +33,15 @@ public function toXML(TokenCollection $tokens): string {
         $writer = new \XMLWriter();
         $writer->openMemory();
         $writer->setIndent(true);
+
         $writer->startDocument();
+        $this->appendToWriter($writer, $tokens);
+        $writer->endDocument();
+
+        return $writer->outputMemory();
+    }
+    
+    public function appendToWriter(XMLWriter $writer, TokenCollection $tokens): void {
         $writer->startElement('source');
         $writer->writeAttribute('xmlns', $this->xmlns->asString());
 
@@ -67,8 +76,5 @@ public function toXML(TokenCollection $tokens): string {
         }
 
         $writer->endElement();
-        $writer->endDocument();
-
-        return $writer->outputMemory();
     }
 }
diff --git a/tests/XMLSerializerTest.php b/tests/XMLSerializerTest.php
index 7cbbbe0..6e71d5f 100644
--- a/tests/XMLSerializerTest.php
+++ b/tests/XMLSerializerTest.php
@@ -25,6 +25,21 @@ public function testCanBeSerializedToXml(): void {
         $this->assertEquals($expected, $serializer->toXML($this->tokens));
     }
 
+    public function testCanAppendToWriter(): void {
+        $expected = \file_get_contents(__DIR__ . '/_files/test.php.xml');
+
+        $writer = new \XMLWriter();
+        $writer->openMemory();
+        $writer->setIndent(true);
+
+        $serializer = new XMLSerializer();
+        $writer->startDocument();
+        $serializer->appendToWriter($writer, $this->tokens);
+        $writer->endDocument();
+
+        $this->assertEquals($expected, $writer->outputMemory());
+    }
+
     public function testCanBeSerializedToDomDocument(): void {
         $serializer = new XMLSerializer();
         $result     = $serializer->toDom($this->tokens);