diff --git a/webseite/classes/Task.php b/webseite/classes/Task.php
index 0aecb01..8b0e3ea 100644
--- a/webseite/classes/Task.php
+++ b/webseite/classes/Task.php
@@ -20,7 +20,14 @@ class Task
     public function __construct(string $text, array $variables)
     {
         $this->text = $text;
-        $this->variables = $variables;
+        $this->variables = array();
+        foreach ($variables as $variable => $value) {
+            if(!is_string($value)) {
+                continue;
+            }
+
+            $this->variables[$variable] = $value;
+        }
     }
 
     /**