diff --git a/tests/e2e/Client.php b/tests/e2e/Client.php
index 0774f1c6fd..0595611570 100644
--- a/tests/e2e/Client.php
+++ b/tests/e2e/Client.php
@@ -303,6 +303,8 @@ class Client
 
             if (is_array($value)) {
                 $output += $this->flatten($value, $finalKey); // @todo: handle name collision here if needed
+            } elseif (is_bool($value)) {
+                $output[$finalKey] = $value ? 'true' : 'false';
             } else {
                 $output[$finalKey] = $value;
             }