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);
                             }