diff --git a/src/LinkORB/Buckaroo/SignatureComposer/Sha1Composer.php b/src/LinkORB/Buckaroo/SignatureComposer/Sha1Composer.php
index 320316c..d49aa58 100644
--- a/src/LinkORB/Buckaroo/SignatureComposer/Sha1Composer.php
+++ b/src/LinkORB/Buckaroo/SignatureComposer/Sha1Composer.php
@@ -38,7 +38,7 @@ protected function sign(array $parameters)
         $signatureString = '';
 
         foreach ($parameters as $key => $value) {
-            $signatureString .= $key . '=' . $value;
+            $signatureString .= $key . '=' . urldecode($value);
         }
 
         $signatureString .= $this->secret;