diff --git a/src/Symfony/Component/ExpressionLanguage/Parser.php b/src/Symfony/Component/ExpressionLanguage/Parser.php
index f0d2321241..db4b5858b1 100644
--- a/src/Symfony/Component/ExpressionLanguage/Parser.php
+++ b/src/Symfony/Component/ExpressionLanguage/Parser.php
@@ -190,7 +190,7 @@ class Parser
 
                             $node = new Node\FunctionNode($token->value, $this->parseArguments());
                         } else {
-                            if (!in_array($token->value, $this->names)) {
+                            if (!in_array($token->value, $this->names, true)) {
                                 throw new SyntaxError(sprintf('Variable "%s" is not valid', $token->value), $token->cursor);
                             }
 
diff --git a/src/Symfony/Component/ExpressionLanguage/Tests/ParserTest.php b/src/Symfony/Component/ExpressionLanguage/Tests/ParserTest.php
index 3be677ca76..4cbab6591f 100644
--- a/src/Symfony/Component/ExpressionLanguage/Tests/ParserTest.php
+++ b/src/Symfony/Component/ExpressionLanguage/Tests/ParserTest.php
@@ -28,6 +28,17 @@ class ParserTest extends \PHPUnit_Framework_TestCase
         $parser->parse($lexer->tokenize('foo'));
     }
 
+    /**
+     * @expectedException        \Symfony\Component\ExpressionLanguage\SyntaxError
+     * @expectedExceptionMessage Variable "foo" is not valid around position 1.
+     */
+    public function testParseWithZeroInNames()
+    {
+        $lexer = new Lexer();
+        $parser = new Parser(array());
+        $parser->parse($lexer->tokenize('foo'), array(0));
+    }
+
     /**
      * @dataProvider getParseData
      */