diff --git a/src/Symfony/Bridge/Twig/Node/TransNode.php b/src/Symfony/Bridge/Twig/Node/TransNode.php
index 3a831829ff..0d09918c5b 100644
--- a/src/Symfony/Bridge/Twig/Node/TransNode.php
+++ b/src/Symfony/Bridge/Twig/Node/TransNode.php
@@ -89,15 +89,24 @@ class TransNode extends \Twig_Node
             return array($body, $vars);
         }
 
-        $current = array();
-        foreach ($vars as $name => $var) {
-            $current[$name] = true;
-        }
-
         preg_match_all('/(?<!%)%([^%]+)%/', $msg, $matches);
-        foreach ($matches[1] as $var) {
-            if (!isset($current['%'.$var.'%'])) {
-                $vars->setNode('%'.$var.'%', new \Twig_Node_Expression_Name($var, $body->getLine()));
+
+        if (version_compare(\Twig_Environment::VERSION, '1.5', '>=')) {
+            foreach ($matches[1] as $var) {
+                $key = new \Twig_Node_Expression_Constant('%'.$var.'%', $body->getLine());
+                if (!$vars->hasElement($key)) {
+                    $vars->addElement(new \Twig_Node_Expression_Name($var, $body->getLine()), $key);
+                }
+            }
+        } else {
+            $current = array();
+            foreach ($vars as $name => $var) {
+                $current[$name] = true;
+            }
+            foreach ($matches[1] as $var) {
+                if (!isset($current['%'.$var.'%'])) {
+                    $vars->setNode('%'.$var.'%', new \Twig_Node_Expression_Name($var, $body->getLine()));
+                }
             }
         }