diff --git a/IntlExtension.php b/IntlExtension.php
index 7278db2..43fd1c6 100644
--- a/IntlExtension.php
+++ b/IntlExtension.php
@@ -156,7 +156,7 @@ public function __construct(?\IntlDateFormatter $dateFormatterPrototype = null,
         $this->numberFormatterPrototype = $numberFormatterPrototype;
     }
 
-    public function getFilters()
+    public function getFilters(): array
     {
         return [
             // internationalized names
@@ -177,7 +177,7 @@ public function getFilters()
         ];
     }
 
-    public function getFunctions()
+    public function getFunctions(): array
     {
         return [
             // internationalized names