diff --git a/services/LocalizationService.php b/services/LocalizationService.php
index 38085c25..5999e27c 100644
--- a/services/LocalizationService.php
+++ b/services/LocalizationService.php
@@ -123,7 +123,7 @@ class LocalizationService
 		}
 	}
 
-	public function __n($number, string $singularForm, string $pluralForm)
+	public function __n($number, string $singularForm, ?string $pluralForm)
 	{
 		$this->CheckAndAddMissingTranslationToPot($singularForm);