diff --git a/lib/MailNotifications.php b/lib/MailNotifications.php
index 208d8ea99..ef7ff2488 100644
--- a/lib/MailNotifications.php
+++ b/lib/MailNotifications.php
@@ -135,11 +135,13 @@ public function sendEmails(int $batchSize, int $sendTime): void {
 		$userEnabled = $this->config->getUserValueForUsers('core', 'enabled', $userIds);
 
 		$fallbackLang = $this->config->getSystemValue('force_language', null);
-		if ($fallbackLang === null) {
-			$fallbackLang = $this->config->getSystemValue('default_language', 'en');
-			$userLanguages = $this->config->getUserValueForUsers('core', 'lang', $userIds);
-		} else {
+		if (is_string($fallbackLang)) {
+			/** @psalm-var array<string, string> $userLanguages */
 			$userLanguages = [];
+		} else {
+			$fallbackLang = $this->config->getSystemValueString('default_language', 'en');
+			/** @psalm-var array<string, string> $userLanguages */
+			$userLanguages = $this->config->getUserValueForUsers('core', 'lang', $userIds);
 		}
 
 		foreach ($userSettings as $settings) {