diff --git a/adminstuds.php b/adminstuds.php
index a9977db..5c6ba56 100644
--- a/adminstuds.php
+++ b/adminstuds.php
@@ -333,7 +333,7 @@ if (isset($_POST['confirm_delete_poll'])) {
 // Delete a slot
 // -------------------------------
 
-if (!empty($_GET['delete_column'])) {
+if (isset($_GET['delete_column'])) {
     $column = filter_input(INPUT_GET, 'delete_column', FILTER_DEFAULT);
     $column = Utils::base64url_decode($column);
 
diff --git a/tpl/part/messages.tpl b/tpl/part/messages.tpl
new file mode 100644
index 0000000..e69de29