diff --git a/src/PowerIdPDisco.php b/src/PowerIdPDisco.php
index 00fad91..d4dc21c 100644
--- a/src/PowerIdPDisco.php
+++ b/src/PowerIdPDisco.php
@@ -342,7 +342,7 @@ public function handleRequest(): void
                 $tab,
                 '/^[a-z_][a-z0-9_-]+$/i',
                 'Tags can contain alphanumeric characters, hyphens and underscores.'
-                . ' They must start with a A-Z or an underscore (supplied: "' . $tab . '")',
+                . ' They must start with a A-Z or an underscore (supplied: \'%s\')',
             );
 
             $translatableTag = "{discopower:tabs:$tab}";