diff --git a/module/VuFind/src/VuFind/I18n/TranslatableString.php b/module/VuFind/src/VuFind/I18n/TranslatableString.php
index c0eab6cb04f4fd7b606a44f9153c512f3d154c08..805d4254a90dc596f942190549cf2799381ff5b5 100644
--- a/module/VuFind/src/VuFind/I18n/TranslatableString.php
+++ b/module/VuFind/src/VuFind/I18n/TranslatableString.php
@@ -60,7 +60,7 @@ class TranslatableString implements TranslatableStringInterface
      */
     public function __construct($string, $displayString)
     {
-        $this->string = $string;
+        $this->string = (string)$string;
         $this->displayString = $displayString;
     }