diff --git a/tests/Util/AppDouble.php b/tests/Util/AppDouble.php
index 1288ec68be..28689425a2 100644
--- a/tests/Util/AppDouble.php
+++ b/tests/Util/AppDouble.php
@@ -43,7 +43,7 @@ class AppDouble extends App
 		$this->isLoggedIn = $isLoggedIn;
 	}
 
-	public function isLoggedIn()
+	public function isLoggedIn(): bool
 	{
 		return $this->isLoggedIn;
 	}