diff --git a/app/Application.php b/app/Application.php
index 80fa59b..1b20503 100644
--- a/app/Application.php
+++ b/app/Application.php
@@ -77,7 +77,7 @@ private static function internalError(string $message = '', int $httpCode = 500)
         http_response_code($httpCode);
         echo "Internal error.";
         if ($message) {
-            echo " $message";
+            echo htmlspecialchars(" $message");
         }
         exit;
     }