diff --git a/lib/private/TemplateLayout.php b/lib/private/TemplateLayout.php
index a710ee856e3..316e122e2c9 100644
--- a/lib/private/TemplateLayout.php
+++ b/lib/private/TemplateLayout.php
@@ -162,7 +162,7 @@ class TemplateLayout extends \OC_Template {
 		if ($this->config->getSystemValue('installed', false) && $renderAs != 'error') {
 			if (\OC::$server->getContentSecurityPolicyNonceManager()->browserSupportsCspV3()) {
 				$jsConfigHelper = new JSConfigHelper(
-					\OC::$server->getL10N('lib', $localeLang),
+					\OC::$server->getL10N('lib', $localeLang ?: $lang),
 					\OC::$server->query(Defaults::class),
 					\OC::$server->getAppManager(),
 					\OC::$server->getSession(),