diff --git a/lib/private/Config/UserConfig.php b/lib/private/Config/UserConfig.php
index 1c6b819571e92..329322da364b9 100644
--- a/lib/private/Config/UserConfig.php
+++ b/lib/private/Config/UserConfig.php
@@ -686,7 +686,7 @@ public function getValueBool(
 		bool $default = false,
 		bool $lazy = false,
 	): bool {
-		$b = strtolower($this->getTypedValue($userId, $app, $key, $default ? 'true' : 'false', $lazy, ValueType::BOOL));
+		$b = strtolower((string)$this->getTypedValue($userId, $app, $key, $default ? 'true' : 'false', $lazy, ValueType::BOOL));
 		return in_array($b, ['1', 'true', 'yes', 'on']);
 	}