diff --git a/src/Database/Countries/Country.php b/src/Database/Countries/Country.php
index 3147598c..e6296477 100644
--- a/src/Database/Countries/Country.php
+++ b/src/Database/Countries/Country.php
@@ -7,6 +7,9 @@
 use Sokil\IsoCodes\Database\Countries;
 use Sokil\IsoCodes\TranslationDriver\TranslatorInterface;
 
+/**
+ * @psalm-immutable
+ */
 class Country
 {
     /**
diff --git a/src/Database/Currencies/Currency.php b/src/Database/Currencies/Currency.php
index dc86d50a..a1f2ff03 100644
--- a/src/Database/Currencies/Currency.php
+++ b/src/Database/Currencies/Currency.php
@@ -7,6 +7,9 @@
 use Sokil\IsoCodes\Database\Currencies;
 use Sokil\IsoCodes\TranslationDriver\TranslatorInterface;
 
+/**
+ * @psalm-immutable
+ */
 class Currency
 {
     /**
diff --git a/src/Database/HistoricCountries/Country.php b/src/Database/HistoricCountries/Country.php
index 111917ee..dd32a4c0 100644
--- a/src/Database/HistoricCountries/Country.php
+++ b/src/Database/HistoricCountries/Country.php
@@ -7,6 +7,9 @@
 use Sokil\IsoCodes\Database\HistoricCountries;
 use Sokil\IsoCodes\TranslationDriver\TranslatorInterface;
 
+/**
+ * @psalm-immutable
+ */
 class Country
 {
     /**
diff --git a/src/Database/Languages/Language.php b/src/Database/Languages/Language.php
index 7987e451..8a1ff129 100644
--- a/src/Database/Languages/Language.php
+++ b/src/Database/Languages/Language.php
@@ -7,6 +7,9 @@
 use Sokil\IsoCodes\Database\Languages;
 use Sokil\IsoCodes\TranslationDriver\TranslatorInterface;
 
+/**
+ * @psalm-immutable
+ */
 class Language
 {
     /**
diff --git a/src/Database/Scripts/Script.php b/src/Database/Scripts/Script.php
index cf006f98..944d595e 100644
--- a/src/Database/Scripts/Script.php
+++ b/src/Database/Scripts/Script.php
@@ -7,6 +7,9 @@
 use Sokil\IsoCodes\Database\Scripts;
 use Sokil\IsoCodes\TranslationDriver\TranslatorInterface;
 
+/**
+ * @psalm-immutable
+ */
 class Script
 {
     /**
diff --git a/src/Database/Subdivisions/Subdivision.php b/src/Database/Subdivisions/Subdivision.php
index 3364e115..041b63e1 100644
--- a/src/Database/Subdivisions/Subdivision.php
+++ b/src/Database/Subdivisions/Subdivision.php
@@ -7,6 +7,9 @@
 use Sokil\IsoCodes\Database\Subdivisions;
 use Sokil\IsoCodes\TranslationDriver\TranslatorInterface;
 
+/**
+ * @psalm-immutable
+ */
 class Subdivision
 {
     /**