diff --git a/src/Country.php b/src/Country.php
index a97d1ac..32f2f12 100644
--- a/src/Country.php
+++ b/src/Country.php
@@ -4,12 +4,12 @@
 final class Country
 {
     public function __construct(
-                                private readonly string $entity,
-                                private readonly string $currency,
-                                private readonly string $alphabeticCode,
-                                private readonly int $numericCode,
-                                private readonly int $minorUnit)
-    {
+        private readonly string $entity,
+        private readonly string $currency,
+        private readonly string $alphabeticCode,
+        private readonly int $numericCode,
+        private readonly int $minorUnit
+    ) {
     }
 
     public function getAlphabeticCode(): string
diff --git a/src/Fetcher.php b/src/Fetcher.php
index 8f32c6f..ba555be 100644
--- a/src/Fetcher.php
+++ b/src/Fetcher.php
@@ -4,19 +4,19 @@
 final class Fetcher
 {
     /**
-     * @var null|array|Country[]
+     * @var array<int, Country>
      */
     private ?array $currentCountries = null;
 
     /**
-     * @var null|array|Country[]
+     * @var array<int, Country>
      */
     private ?array $historicCountries = null;
 
     public function __construct(
-                                private readonly string $currentLocation,
-                                private readonly string $historicLocation)
-    {
+        private readonly string $currentLocation,
+        private readonly string $historicLocation
+    ) {
     }
 
     /**
diff --git a/src/Serializer.php b/src/Serializer.php
index 36dfc07..f012291 100644
--- a/src/Serializer.php
+++ b/src/Serializer.php
@@ -4,7 +4,7 @@
 interface Serializer
 {
     /**
-     * @param Country[] $countries
+     * @param array<int|string, Country> $countries
      */
     public function serialize(array $countries): string;
 }
diff --git a/src/Serializer/JsonSerializer.php b/src/Serializer/JsonSerializer.php
index 3e73f44..fa8a236 100644
--- a/src/Serializer/JsonSerializer.php
+++ b/src/Serializer/JsonSerializer.php
@@ -7,7 +7,7 @@
 final class JsonSerializer implements Serializer
 {
     /**
-     * @param array|Country[] $countries
+     * @param array<int|string, Country> $countries
      * @throws \JsonException
      */
     public function serialize(array $countries): string
diff --git a/src/Serializer/PhpExportSerializer.php b/src/Serializer/PhpExportSerializer.php
index c937855..0293844 100644
--- a/src/Serializer/PhpExportSerializer.php
+++ b/src/Serializer/PhpExportSerializer.php
@@ -7,7 +7,7 @@
 final class PhpExportSerializer implements Serializer
 {
     /**
-     * @param array|Country[] $countries
+     * @param array<int|string, Country> $countries
      */
     public function serialize(array $countries): string
     {
diff --git a/src/Serializer/YamlSerializer.php b/src/Serializer/YamlSerializer.php
index d99ab57..fc6c6a6 100644
--- a/src/Serializer/YamlSerializer.php
+++ b/src/Serializer/YamlSerializer.php
@@ -9,7 +9,7 @@
 final class YamlSerializer implements Serializer
 {
     /**
-     * @param array|Country[] $countries
+     * @param array<int|string, Country> $countries
      */
     public function serialize(array $countries): string
     {