diff --git a/src/Twig/IcuFormattingExtension.php b/src/Twig/IcuFormattingExtension.php
index 4567505..fb31566 100644
--- a/src/Twig/IcuFormattingExtension.php
+++ b/src/Twig/IcuFormattingExtension.php
@@ -25,7 +25,7 @@ public function __construct(FormatterInterface $formatter, TranslatorInterface $
         $this->translator = $translator;
     }
 
-    public function getFilters()
+    public function getFilters(): array
     {
         return [
             new TwigFilter('icu_format', [$this, 'format']),