diff --git a/src/NodeInterface.php b/src/NodeInterface.php
index 8fe28eb..973cd3d 100644
--- a/src/NodeInterface.php
+++ b/src/NodeInterface.php
@@ -8,6 +8,13 @@
  * indicate they support the Node API.
  */
 interface NodeInterface {
+
+  /**
+   * Get the filename of the node.
+   * @return string
+   */
+  public function getFilename();
+
   /**
    * Get the line number of the node.
    * @return int
diff --git a/src/ParentNode.php b/src/ParentNode.php
index 91f7507..1626916 100644
--- a/src/ParentNode.php
+++ b/src/ParentNode.php
@@ -404,6 +404,14 @@ public function acceptVisitor(VisitorInterface $visitor) {
     $visitor->visitEnd($this);
   }
 
+  public function getFilename() {
+    if ($this->head === NULL) {
+      return $this->parent->getFilename();
+    }
+    $child = $this->head;
+    return $child->getFilename();
+  }
+
   public function getLineNumber() {
     if ($this->head === NULL) {
       return $this->parent->getLineNumber();
diff --git a/src/Parser.php b/src/Parser.php
index 1b7b442..53faefe 100644
--- a/src/Parser.php
+++ b/src/Parser.php
@@ -97,12 +97,6 @@ class Parser {
    */
   private static $visibilityTypes = [T_PUBLIC, T_PROTECTED, T_PRIVATE];
 
-  /**
-   * Filename being parsed.
-   * @var string
-   */
-  private $filename;
-
   /**
    * Iterator over PHP tokens.
    * @var TokenIterator
@@ -235,8 +229,8 @@ public static function parseSource($source, $filename = NULL) {
       $tokenizer = new Tokenizer();
       $parser = new self();
     }
+    $tokenizer->setFileName($filename);
     $tokens = $tokenizer->getAll($source);
-    $parser->filename = $filename;
     return $parser->buildTree(new TokenIterator($tokens));
   }
 
@@ -285,7 +279,7 @@ private function templateStatementList(ParentNode $node) {
       }
       else {
         throw new ParserException(
-          $this->filename,
+          $this->iterator->getFilename(),
           $this->iterator->getLineNumber(),
           $this->iterator->getColumnNumber(),
           'expected PHP opening tag, but got ' . $this->iterator->current()->getText());
@@ -723,7 +717,7 @@ private function caseStatement($terminator) {
       $node->addChild($this->expr(), 'matchOn');
       if (!$this->tryMatch(':', $node, NULL, TRUE, TRUE) && !$this->tryMatch(';', $node, NULL, TRUE, TRUE)) {
         throw new ParserException(
-          $this->filename,
+          $this->iterator->getFilename(),
           $this->iterator->getLineNumber(),
           $this->iterator->getColumnNumber(),
           'expected :');
@@ -739,7 +733,7 @@ private function caseStatement($terminator) {
       $this->mustMatch(T_DEFAULT, $node);
       if (!$this->tryMatch(':', $node, NULL, TRUE, TRUE) && !$this->tryMatch(';', $node, NULL, TRUE, TRUE)) {
         throw new ParserException(
-          $this->filename,
+          $this->iterator->getFilename(),
           $this->iterator->getLineNumber(),
           $this->iterator->getColumnNumber(),
           'expected :');
@@ -751,7 +745,7 @@ private function caseStatement($terminator) {
       return $node;
     }
     throw new ParserException(
-      $this->filename,
+      $this->iterator->getFilename(),
       $this->iterator->getLineNumber(),
       $this->iterator->getColumnNumber(),
       "expected case or default");
@@ -886,7 +880,7 @@ private function globalVar() {
       }
     }
     throw new ParserException(
-      $this->filename,
+      $this->iterator->getFilename(),
       $this->iterator->getLineNumber(),
       $this->iterator->getColumnNumber(),
       'expected a global variable (eg. T_VARIABLE)');
@@ -1229,13 +1223,13 @@ private function expr($static = FALSE) {
       }
       else {
         throw new ParserException(
-          $this->filename,
+          $this->iterator->getFilename(),
           $this->iterator->getLineNumber(),
           $this->iterator->getColumnNumber(),
           "invalid expression");
       }
     }
-    return $this->expressionParser->parse($expression_nodes, $this->filename);
+    return $this->expressionParser->parse($expression_nodes, $this->iterator->getFilename());
   }
 
   /**
@@ -1459,7 +1453,7 @@ private function exprOperand() {
         return $this->backtick();
     }
     throw new ParserException(
-      $this->filename,
+      $this->iterator->getFilename(),
       $this->iterator->getLineNumber(),
       $this->iterator->getColumnNumber(),
       "excepted expression operand but got " . $this->current->getTypeName());
@@ -1721,7 +1715,7 @@ private function encapsVar() {
       if ($this->tryMatch('[', $node)) {
         if (!in_array($this->currentType, $offset_types)) {
           throw new ParserException(
-            $this->filename,
+            $this->iterator->getFilename(),
             $this->iterator->getLineNumber(),
             $this->iterator->getColumnNumber(),
             'expected encaps_var_offset (T_STRING or T_NUM_STRING or T_VARIABLE)');
@@ -1735,7 +1729,7 @@ private function encapsVar() {
       return $node;
     }
     throw new ParserException(
-      $this->filename,
+      $this->iterator->getFilename(),
       $this->iterator->getLineNumber(),
       $this->iterator->getColumnNumber(),
       'expected encaps variable');
@@ -1897,7 +1891,7 @@ private function variable() {
         }
     }
     throw new ParserException(
-      $this->filename,
+      $this->iterator->getFilename(),
       $this->iterator->getLineNumber(),
       $this->iterator->getColumnNumber(),
       "expected variable");
@@ -2272,7 +2266,7 @@ private function innerStatement() {
     switch ($this->currentType) {
       case T_HALT_COMPILER:
         throw new ParserException(
-          $this->filename,
+          $this->iterator->getFilename(),
           $this->iterator->getLineNumber(),
           $this->iterator->getColumnNumber(),
           "__halt_compiler can only be used from the outermost scope");
@@ -2491,7 +2485,7 @@ private function classStatement($is_abstract) {
         case T_PRIVATE:
           if ($modifiers->getVisibility()) {
             throw new ParserException(
-              $this->filename,
+              $this->iterator->getFilename(),
               $this->iterator->getLineNumber(),
               $this->iterator->getColumnNumber(),
               "can only have one visibility modifier on class member/method."
@@ -2502,7 +2496,7 @@ private function classStatement($is_abstract) {
         case T_STATIC:
           if ($modifiers->getStatic()) {
             throw new ParserException(
-              $this->filename,
+              $this->iterator->getFilename(),
               $this->iterator->getLineNumber(),
               $this->iterator->getColumnNumber(),
               "duplicate modifier");
@@ -2512,14 +2506,14 @@ private function classStatement($is_abstract) {
         case T_FINAL:
           if ($modifiers->getFinal()) {
             throw new ParserException(
-              $this->filename,
+              $this->iterator->getFilename(),
               $this->iterator->getLineNumber(),
               $this->iterator->getColumnNumber(),
               "duplicate modifier");
           }
           if ($modifiers->getAbstract()) {
             throw new ParserException(
-              $this->filename,
+              $this->iterator->getFilename(),
               $this->iterator->getLineNumber(),
               $this->iterator->getColumnNumber(),
               "can not use final modifier on abstract method");
@@ -2529,21 +2523,21 @@ private function classStatement($is_abstract) {
         case T_ABSTRACT:
           if ($modifiers->getAbstract()) {
             throw new ParserException(
-              $this->filename,
+              $this->iterator->getFilename(),
               $this->iterator->getLineNumber(),
               $this->iterator->getColumnNumber(),
               "duplicate modifier");
           }
           if ($modifiers->getFinal()) {
             throw new ParserException(
-              $this->filename,
+              $this->iterator->getFilename(),
               $this->iterator->getLineNumber(),
               $this->iterator->getColumnNumber(),
               "can not use abstract modifier on final method");
           }
           if (!$is_abstract) {
             throw new ParserException(
-              $this->filename,
+              $this->iterator->getFilename(),
               $this->iterator->getLineNumber(),
               $this->iterator->getColumnNumber(),
               "can not use abstract modifier in non-abstract class");
@@ -2556,14 +2550,14 @@ private function classStatement($is_abstract) {
           return $this->classMemberList($doc_comment, $modifiers);
         default:
           throw new ParserException(
-            $this->filename,
+            $this->iterator->getFilename(),
             $this->iterator->getLineNumber(),
             $this->iterator->getColumnNumber(),
             "invalid class statement");
       }
     }
     throw new ParserException(
-      $this->filename,
+      $this->iterator->getFilename(),
       $this->iterator->getLineNumber(),
       $this->iterator->getColumnNumber(),
       "invalid class statement");
@@ -2580,14 +2574,14 @@ private function classMemberList($doc_comment, ModifiersNode $modifiers) {
     // Modifier checks
     if ($modifiers->getAbstract()) {
       throw new ParserException(
-        $this->filename,
+        $this->iterator->getFilename(),
         $this->iterator->getLineNumber(),
         $this->iterator->getColumnNumber(),
         "members can not be declared abstract");
     }
     if ($modifiers->getFinal()) {
       throw new ParserException(
-        $this->filename,
+        $this->iterator->getFilename(),
         $this->iterator->getLineNumber(),
         $this->iterator->getColumnNumber(),
         "members can not be declared final");
@@ -2766,7 +2760,7 @@ private function interfaceMethod() {
     while (in_array($this->currentType, $visibility_keyword_types)) {
       if ($node->getVisibility()) {
         throw new ParserException(
-          $this->filename,
+          $this->iterator->getFilename(),
           $this->iterator->getLineNumber(),
           $this->iterator->getColumnNumber(),
           "can only have one visibility modifier on interface method."
@@ -2797,7 +2791,7 @@ private function traitDeclaration() {
     $node->addChild($name_node, 'name');
     if ($this->currentType === T_EXTENDS) {
       throw new ParserException(
-        $this->filename,
+        $this->iterator->getFilename(),
         $this->iterator->getLineNumber(),
         $this->iterator->getColumnNumber(),
         'Traits can only be composed from other traits with the \'use\' keyword.'
@@ -2805,7 +2799,7 @@ private function traitDeclaration() {
     }
     if ($this->currentType === T_IMPLEMENTS) {
       throw new ParserException(
-        $this->filename,
+        $this->iterator->getFilename(),
         $this->iterator->getLineNumber(),
         $this->iterator->getColumnNumber(),
         'Traits can not implement interfaces.'
@@ -2947,7 +2941,7 @@ private function matchDocComment(ParentNode $parent, $property_name = 'docCommen
   private function mustMatch($expected_type, ParentNode $parent, $property_name = NULL, $maybe_last = FALSE, $capture_doc_comment = FALSE) {
     if ($this->currentType !== $expected_type) {
       throw new ParserException(
-        $this->filename,
+        $this->iterator->getFilename(),
         $this->iterator->getLineNumber(),
         $this->iterator->getColumnNumber(),
         'expected ' . TokenNode::typeName($expected_type));
@@ -3022,7 +3016,7 @@ private function tryMatchToken($expected_types) {
   private function mustMatchToken($expected_type) {
     if ($this->currentType !== $expected_type) {
       throw new ParserException(
-        $this->filename,
+        $this->iterator->getFilename(),
         $this->iterator->getLineNumber(),
         $this->iterator->getColumnNumber(),
         'expected ' . TokenNode::typeName($expected_type));
diff --git a/src/TokenIterator.php b/src/TokenIterator.php
index 91ea18f..f27ab10 100644
--- a/src/TokenIterator.php
+++ b/src/TokenIterator.php
@@ -76,6 +76,17 @@ public function hasNext() {
     return $this->position + 1 < $this->length;
   }
 
+  /**
+   * @return string
+   */
+  public function getFilename() {
+    $token = $this->current();
+    if ($token === NULL) {
+      $token = $this->tokens[$this->length - 1];
+    }
+    return $token->getFilename();
+  }
+
   /**
    * @return int
    */
diff --git a/src/TokenNode.php b/src/TokenNode.php
index 20230f7..18e5c01 100644
--- a/src/TokenNode.php
+++ b/src/TokenNode.php
@@ -20,6 +20,11 @@ class TokenNode extends Node {
    */
   protected $lineNo;
 
+  /**
+   * @var string
+   */
+  protected $filename;
+
   /**
    * @var int
    */
@@ -39,20 +44,29 @@ class TokenNode extends Node {
    * Construct token.
    * @param int $type
    * @param string $text
+   * @param string $filename
    * @param int $lineNo
    * @param int $newlineCount
    * @param int $colNo
    * @param int $byteOffset
    */
-  public function __construct($type, $text, $lineNo = -1, $newlineCount = -1, $colNo = -1, $byteOffset = -1) {
+  public function __construct($type, $text, $filename = '', $lineNo = -1, $newlineCount = -1, $colNo = -1, $byteOffset = -1) {
     $this->type = $type;
     $this->text = $text;
+    $this->filename = $filename;
     $this->lineNo = $lineNo;
     $this->newlineCount = $newlineCount;
     $this->colNo = $colNo;
     $this->byteOffset = $byteOffset;
   }
 
+  /**
+   * @return string
+   */
+  public function getFilename() {
+    return $this->filename;
+  }
+
   /**
    * @return int
    */
diff --git a/src/Tokenizer.php b/src/Tokenizer.php
index 7987679..8a0699c 100644
--- a/src/Tokenizer.php
+++ b/src/Tokenizer.php
@@ -18,6 +18,7 @@
  * Convert PHP source into an array of tokens.
  */
 class Tokenizer {
+  private $filename;
   private $lineNo;
   private $colNo;
   private $byteOffset;
@@ -30,6 +31,7 @@ private function parseToken($token) {
       $type = $token;
       $text = $token;
     }
+    $filename = $this->filename;
     $lineNo = $this->lineNo;
     $colNo = $this->colNo;
     $byteOffset = $this->byteOffset;
@@ -42,43 +44,43 @@ private function parseToken($token) {
       $this->colNo += $length;
     }
     $this->byteOffset += $length;
-    return $this->createToken($type, $text, $lineNo, $newlineCount, $colNo, $byteOffset);
+    return $this->createToken($type, $text, $filename, $lineNo, $newlineCount, $colNo, $byteOffset);
   }
 
-  private function createToken($type, $text, $lineNo, $newlineCount, $colNo, $byteOffset) {
+  private function createToken($type, $text, $filename, $lineNo, $newlineCount, $colNo, $byteOffset) {
     switch ($type) {
       case T_VARIABLE:
-        return new VariableNode($type, $text, $lineNo, $newlineCount, $colNo, $byteOffset);
+        return new VariableNode($type, $text, $filename, $lineNo, $newlineCount, $colNo, $byteOffset);
       case T_LNUMBER:
-        return new IntegerNode($type, $text, $lineNo, $newlineCount, $colNo, $byteOffset);
+        return new IntegerNode($type, $text, $filename, $lineNo, $newlineCount, $colNo, $byteOffset);
       case T_DNUMBER:
-        return new FloatNode($type, $text, $lineNo, $newlineCount, $colNo, $byteOffset);
+        return new FloatNode($type, $text, $filename, $lineNo, $newlineCount, $colNo, $byteOffset);
       case T_CONSTANT_ENCAPSED_STRING:
-        return new StringNode($type, $text, $lineNo, $newlineCount, $colNo, $byteOffset);
+        return new StringNode($type, $text, $filename, $lineNo, $newlineCount, $colNo, $byteOffset);
       case T_LINE:
-        return new LineMagicConstantNode($type, $text, $lineNo, $newlineCount, $colNo, $byteOffset);
+        return new LineMagicConstantNode($type, $text, $filename, $lineNo, $newlineCount, $colNo, $byteOffset);
       case T_FILE:
-        return new FileMagicConstantNode($type, $text, $lineNo, $newlineCount, $colNo, $byteOffset);
+        return new FileMagicConstantNode($type, $text, $filename, $lineNo, $newlineCount, $colNo, $byteOffset);
       case T_DIR:
-        return new DirMagicConstantNode($type, $text, $lineNo, $newlineCount, $colNo, $byteOffset);
+        return new DirMagicConstantNode($type, $text, $filename, $lineNo, $newlineCount, $colNo, $byteOffset);
       case T_FUNC_C:
-        return new FunctionMagicConstantNode($type, $text, $lineNo, $newlineCount, $colNo, $byteOffset);
+        return new FunctionMagicConstantNode($type, $text, $filename, $lineNo, $newlineCount, $colNo, $byteOffset);
       case T_CLASS_C:
-        return new ClassMagicConstantNode($type, $text, $lineNo, $newlineCount, $colNo, $byteOffset);
+        return new ClassMagicConstantNode($type, $text, $filename, $lineNo, $newlineCount, $colNo, $byteOffset);
       case T_TRAIT_C:
-        return new TraitMagicConstantNode($type, $text, $lineNo, $newlineCount, $colNo, $byteOffset);
+        return new TraitMagicConstantNode($type, $text, $filename, $lineNo, $newlineCount, $colNo, $byteOffset);
       case T_METHOD_C:
-        return new MethodMagicConstantNode($type, $text, $lineNo, $newlineCount, $colNo, $byteOffset);
+        return new MethodMagicConstantNode($type, $text, $filename, $lineNo, $newlineCount, $colNo, $byteOffset);
       case T_NS_C:
-        return new NamespaceMagicConstantNode($type, $text, $lineNo, $newlineCount, $colNo, $byteOffset);
+        return new NamespaceMagicConstantNode($type, $text, $filename, $lineNo, $newlineCount, $colNo, $byteOffset);
       case T_COMMENT:
-        return new CommentNode($type, $text, $lineNo, $newlineCount, $colNo, $byteOffset);
+        return new CommentNode($type, $text, $filename, $lineNo, $newlineCount, $colNo, $byteOffset);
       case T_DOC_COMMENT:
-        return new DocCommentNode($type, $text, $lineNo, $newlineCount, $colNo, $byteOffset);
+        return new DocCommentNode($type, $text, $filename, $lineNo, $newlineCount, $colNo, $byteOffset);
       case T_WHITESPACE:
-        return new WhitespaceNode($type, $text, $lineNo, $newlineCount, $colNo, $byteOffset);
+        return new WhitespaceNode($type, $text, $filename, $lineNo, $newlineCount, $colNo, $byteOffset);
       default:
-        return new TokenNode($type, $text, $lineNo, $newlineCount, $colNo, $byteOffset);
+        return new TokenNode($type, $text, $filename, $lineNo, $newlineCount, $colNo, $byteOffset);
     }
   }
 
@@ -98,4 +100,13 @@ public function getAll($source) {
     }
     return $tokens;
   }
+
+  /**
+   * Sets the filename.
+   *
+   * @param string $filename
+   */
+  public function setFileName($filename) {
+    $this->filename = $filename;
+  }
 }
diff --git a/tests/ParentNodeTest.php b/tests/ParentNodeTest.php
index c11b0c9..f6d6b8e 100644
--- a/tests/ParentNodeTest.php
+++ b/tests/ParentNodeTest.php
@@ -148,7 +148,7 @@ public function testWalkAbort() {
   }
 
   public function testSourcePosition() {
-    $token = new TokenNode(T_STRING, 'test', 4, 0, 2);
+    $token = new TokenNode(T_STRING, 'test', '', 4, 0, 2);
     $grandparent = $this->createParentNode();
     $grandparent->append($token);
     $parent = $this->createParentNode();
diff --git a/tests/TokenIteratorTest.php b/tests/TokenIteratorTest.php
index c03b19f..fc0f671 100644
--- a/tests/TokenIteratorTest.php
+++ b/tests/TokenIteratorTest.php
@@ -3,7 +3,7 @@
 
 class TokenIteratorTest extends \PHPUnit_Framework_TestCase {
   public function testSingle() {
-    $test = new TokenNode(T_STRING, 'test', 1, 0, 1, 0);
+    $test = new TokenNode(T_STRING, 'test', '', 1, 0, 1, 0);
     $iterator = new TokenIterator([$test]);
     $peek = $iterator->peek(0);
     $this->assertSame($test, $peek);