diff --git a/src/Translator.php b/src/Translator.php
index 2bf1d15..4e169e6 100644
--- a/src/Translator.php
+++ b/src/Translator.php
@@ -167,7 +167,7 @@ protected function translatePlural(
     protected function getTranslation(?string $domain, ?string $context, string $original): ?array
     {
         if ($domain === null) {
-            $domain = $this->domain;
+            $domain = (string) $this->domain;
         }
 
         if ($context === null) {
@@ -186,7 +186,7 @@ protected function getTranslation(?string $domain, ?string $context, string $ori
     protected function getPluralIndex(?string $domain, int $n, bool $fallback): int
     {
         if ($domain === null) {
-            $domain = $this->domain;
+            $domain = (string) $this->domain;
         }
 
         //Not loaded domain or translation, use a fallback