diff --git a/exercises/tb_exercise.php b/exercises/tb_exercise.php
index f83832212171ee44aa036af0b49d4dcf615c871f..615f521a671c3c9b3f3c8a7a37919bf9b73da08f 100644
--- a/exercises/tb_exercise.php
+++ b/exercises/tb_exercise.php
@@ -181,7 +181,7 @@ class tb_exercise extends Exercise
     /**
      * Trigger download of uploaded file for a selected solution.
      */
-    public function download_action()
+    public function download_action($controller)
     {
         vips_require_status('autor');
 
@@ -215,7 +215,7 @@ class tb_exercise extends Exercise
     /**
      * Trigger download of all uploaded files for a selected solution.
      */
-    public function download_zip_action()
+    public function download_zip_action($controller)
     {
         vips_require_status('autor');