diff --git a/.github/workflows/phpstan.yml b/.github/workflows/phpstan.yml
new file mode 100644
index 0000000..88be9bf
--- /dev/null
+++ b/.github/workflows/phpstan.yml
@@ -0,0 +1,10 @@
+name: PHPStan
+
+on:
+  push
+
+jobs:
+  phpstan:
+    uses: stefanzweifel/reusable-workflows/.github/workflows/phpstan.yml@main
+    with:
+      php_version: '8.3'
diff --git a/.github/workflows/psalm.yml b/.github/workflows/psalm.yml
deleted file mode 100644
index b18170b..0000000
--- a/.github/workflows/psalm.yml
+++ /dev/null
@@ -1,26 +0,0 @@
-name: Psalm
-
-on:
-  push:
-    paths:
-      - '**.php'
-      - 'psalm.xml'
-
-jobs:
-  psalm:
-    name: psalm
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v3
-
-      - name: Setup PHP
-        uses: shivammathur/setup-php@v2
-        with:
-          php-version: 8.2
-          extensions: dom, curl, libxml, mbstring, zip, pcntl, pdo, sqlite, pdo_sqlite, bcmath, soap, intl, gd, exif, iconv, imagick
-
-      - name: Run composer install
-        run: composer install -n --prefer-dist
-
-      - name: Run psalm
-        run: ./vendor/bin/psalm
diff --git a/composer.json b/composer.json
index e231e29..669c604 100644
--- a/composer.json
+++ b/composer.json
@@ -23,10 +23,10 @@
     "require-dev": {
         "phpunit/phpunit": "^10.1",
         "friendsofphp/php-cs-fixer": "^3",
-        "vimeo/psalm": "^5.0",
         "league/csv": "^9.7",
         "symfony/console": "^6.0",
-        "rector/rector": "^0.15.24"
+        "rector/rector": "^0.15.24",
+        "phpstan/phpstan": "^1.10"
     },
     "autoload": {
         "psr-4": {
diff --git a/phpstan.neon b/phpstan.neon
new file mode 100644
index 0000000..46b0f47
--- /dev/null
+++ b/phpstan.neon
@@ -0,0 +1,5 @@
+parameters:
+    level: 5
+    paths:
+        - src
+        - tests
diff --git a/psalm.xml b/psalm.xml
deleted file mode 100644
index 30258a7..0000000
--- a/psalm.xml
+++ /dev/null
@@ -1,15 +0,0 @@
-<?xml version="1.0"?>
-<psalm
-    errorLevel="3"
-    resolveFromConfigFile="true"
-    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xmlns="https://getpsalm.org/schema/config"
-    xsi:schemaLocation="https://getpsalm.org/schema/config vendor/vimeo/psalm/config.xsd"
->
-    <projectFiles>
-        <directory name="src" />
-        <ignoreFiles>
-            <directory name="vendor" />
-        </ignoreFiles>
-    </projectFiles>
-</psalm>
diff --git a/src/Exceptions/CantonException.php b/src/Exceptions/CantonException.php
index 7b49ef4..e390ac4 100644
--- a/src/Exceptions/CantonException.php
+++ b/src/Exceptions/CantonException.php
@@ -8,16 +8,19 @@ class CantonException extends Exception
 {
     public static function notFoundForAbbreviation(string $abbreviation): self
     {
+        /** @phpstan-ignore-next-line */
         return new static("Couldn't find Canton for given abbreviation: {$abbreviation}");
     }
 
     public static function notFoundForName(string $name): self
     {
+        /** @phpstan-ignore-next-line */
         return new static("Couldn't find Canton for given name: {$name}");
     }
 
     public static function notFoundForZipcode(int $zipcode): self
     {
+        /** @phpstan-ignore-next-line */
         return new static("Couldn't find Canton for given zipcode: {$zipcode}");
     }
 }
diff --git a/tests/CantonManagerTest.php b/tests/CantonManagerTest.php
index a7bb825..c71532a 100644
--- a/tests/CantonManagerTest.php
+++ b/tests/CantonManagerTest.php
@@ -10,7 +10,7 @@
 class CantonManagerTest extends TestCase
 {
     #[Test]
-    public function it_returns_correct_canton_instance_for_abbreviation()
+    public function it_returns_correct_canton_instance_for_abbreviation(): void
     {
         $canton = new CantonManager();
         $canton = $canton->getByAbbreviation('ZH');
@@ -22,7 +22,7 @@ public function it_returns_correct_canton_instance_for_abbreviation()
     }
 
     #[Test]
-    public function it_returns_correct_canton_if_abbreviation_is_lowercase()
+    public function it_returns_correct_canton_if_abbreviation_is_lowercase(): void
     {
         $cantonManager = new CantonManager();
 
@@ -46,7 +46,7 @@ public function it_returns_correct_canton_if_abbreviation_is_lowercase()
     }
 
     #[Test]
-    public function it_throws_exception_if_no_canton_for_abbreviation_is_found()
+    public function it_throws_exception_if_no_canton_for_abbreviation_is_found(): void
     {
         $this->expectException(CantonException::class);
 
@@ -55,7 +55,7 @@ public function it_throws_exception_if_no_canton_for_abbreviation_is_found()
     }
 
     #[Test]
-    public function it_returns_correct_canton_instance_for_name()
+    public function it_returns_correct_canton_instance_for_name(): void
     {
         $canton = new CantonManager();
         $result = $canton->getByName('Zürich');
@@ -64,7 +64,7 @@ public function it_returns_correct_canton_instance_for_name()
     }
 
     #[Test]
-    public function it_throws_exception_if_not_canton_for_name_is_found()
+    public function it_throws_exception_if_not_canton_for_name_is_found(): void
     {
         $this->expectException(CantonException::class);
 
@@ -73,7 +73,7 @@ public function it_throws_exception_if_not_canton_for_name_is_found()
     }
 
     #[Test]
-    public function it_returns_canton_for_zipcode()
+    public function it_returns_canton_for_zipcode(): void
     {
         $canton = new CantonManager();
         $result = $canton->getByZipcode(3005);
@@ -84,7 +84,7 @@ public function it_returns_canton_for_zipcode()
     }
 
     #[Test]
-    public function it_throws_exception_if_no_canton_for_zipcode_could_be_found()
+    public function it_throws_exception_if_no_canton_for_zipcode_could_be_found(): void
     {
         $this->expectException(CantonException::class);
 
@@ -93,7 +93,7 @@ public function it_throws_exception_if_no_canton_for_zipcode_could_be_found()
     }
 
     #[Test]
-    public function it_throws_exception_if_lichtenstein_zipcode_is_searched_for()
+    public function it_throws_exception_if_lichtenstein_zipcode_is_searched_for(): void
     {
         $this->expectException(CantonException::class);
 
diff --git a/tests/CantonSearchTest.php b/tests/CantonSearchTest.php
index b09476d..9b09bde 100644
--- a/tests/CantonSearchTest.php
+++ b/tests/CantonSearchTest.php
@@ -10,7 +10,7 @@
 class CantonSearchTest extends TestCase
 {
     #[Test]
-    public function it_finds_canton_by_abbreviation()
+    public function it_finds_canton_by_abbreviation(): void
     {
         $cantonSearch = new CantonSearch();
         $canton = $cantonSearch->findByAbbreviation('SH');
@@ -20,7 +20,7 @@ public function it_finds_canton_by_abbreviation()
     }
 
     #[Test]
-    public function it_returns_null_if_no_canton_for_abbreviation_was_found()
+    public function it_returns_null_if_no_canton_for_abbreviation_was_found(): void
     {
         $cantonSearch = new CantonSearch();
         $canton = $cantonSearch->findByAbbreviation('foo');
@@ -29,7 +29,7 @@ public function it_returns_null_if_no_canton_for_abbreviation_was_found()
     }
 
     #[Test]
-    public function it_finds_canton_by_name()
+    public function it_finds_canton_by_name(): void
     {
         $cantonSearch = new CantonSearch();
         $canton = $cantonSearch->findByName('Zürich');
@@ -40,7 +40,7 @@ public function it_finds_canton_by_name()
     }
 
     #[Test]
-    public function it_returns_null_if_no_canton_for_name_was_found()
+    public function it_returns_null_if_no_canton_for_name_was_found(): void
     {
         $cantonSearch = new CantonSearch();
         $canton = $cantonSearch->findByName('foo');
diff --git a/tests/CantonTest.php b/tests/CantonTest.php
index c68d167..8c5d9d1 100644
--- a/tests/CantonTest.php
+++ b/tests/CantonTest.php
@@ -24,7 +24,7 @@ protected function getExampleCanton(): array
     }
 
     #[Test]
-    public function it_sets_language()
+    public function it_sets_language(): void
     {
         $canton = new Canton($this->getExampleCanton());
         $canton->setLanguage('fr');
@@ -33,7 +33,7 @@ public function it_sets_language()
     }
 
     #[Test]
-    public function it_transformers_uppercase_language_string_to_lowercase()
+    public function it_transformers_uppercase_language_string_to_lowercase(): void
     {
         $canton = new Canton($this->getExampleCanton());
         $canton->setLanguage('DE');
@@ -42,7 +42,7 @@ public function it_transformers_uppercase_language_string_to_lowercase()
     }
 
     #[Test]
-    public function it_only_allows_national_languages()
+    public function it_only_allows_national_languages(): void
     {
         $this->expectException(InvalidLanguageException::class);
 
@@ -51,7 +51,7 @@ public function it_only_allows_national_languages()
     }
 
     #[Test]
-    public function it_sets_and_returns_abbreviation()
+    public function it_sets_and_returns_abbreviation(): void
     {
         $canton = new Canton($this->getExampleCanton());
 
@@ -59,7 +59,7 @@ public function it_sets_and_returns_abbreviation()
     }
 
     #[Test]
-    public function it_sets_names_array()
+    public function it_sets_names_array(): void
     {
         $canton = new Canton($this->getExampleCanton());
 
@@ -70,7 +70,7 @@ public function it_sets_names_array()
     }
 
     #[Test]
-    public function it_returns_correct_name_for_given_language()
+    public function it_returns_correct_name_for_given_language(): void
     {
         $canton = new Canton($this->getExampleCanton());
 
diff --git a/tests/CantonsTest.php b/tests/CantonsTest.php
index 96016e5..3d44289 100644
--- a/tests/CantonsTest.php
+++ b/tests/CantonsTest.php
@@ -10,7 +10,7 @@
 class CantonsTest extends TestCase
 {
     #[Test]
-    public function it_returns_json_source_as_array()
+    public function it_returns_json_source_as_array(): void
     {
         $cantons = new Cantons();
 
@@ -18,7 +18,7 @@ public function it_returns_json_source_as_array()
     }
 
     #[Test]
-    public function it_contains_abbreviation_and_name()
+    public function it_contains_abbreviation_and_name(): void
     {
         $cantons = (new Cantons())->getAll();
 
@@ -31,7 +31,7 @@ public function it_contains_abbreviation_and_name()
     }
 
     #[Test]
-    public function it_returns_an_array_with_abbreviation_as_key_and_name_as_value()
+    public function it_returns_an_array_with_abbreviation_as_key_and_name_as_value(): void
     {
         $cantons = (new Cantons())->getAllAsArray();
 
@@ -43,7 +43,7 @@ public function it_returns_an_array_with_abbreviation_as_key_and_name_as_value()
     }
 
     #[Test]
-    public function it_returns_an_array_with_abbreviation_and_name_but_in_a_different_language()
+    public function it_returns_an_array_with_abbreviation_and_name_but_in_a_different_language(): void
     {
         $cantons = (new Cantons())->getAllAsArray('de');
 
@@ -55,7 +55,7 @@ public function it_returns_an_array_with_abbreviation_and_name_but_in_a_differen
     }
 
     #[Test]
-    public function it_throws_an_exception_if_passed_langauge_is_not_available()
+    public function it_throws_an_exception_if_passed_langauge_is_not_available(): void
     {
         $this->expectException(Exception::class);
 
diff --git a/tests/ZipcodeSearchTest.php b/tests/ZipcodeSearchTest.php
index 0413e6d..f15a5a3 100644
--- a/tests/ZipcodeSearchTest.php
+++ b/tests/ZipcodeSearchTest.php
@@ -9,7 +9,7 @@
 class ZipcodeSearchTest extends TestCase
 {
     #[Test]
-    public function it_returns_dataset_as_array()
+    public function it_returns_dataset_as_array(): void
     {
         $cantonSearch = new ZipcodeSearch();
 
@@ -17,7 +17,7 @@ public function it_returns_dataset_as_array()
     }
 
     #[Test]
-    public function it_finds_canton_by_zipcode()
+    public function it_finds_canton_by_zipcode(): void
     {
         $zipcodeSearch = new ZipcodeSearch();
 
@@ -29,7 +29,7 @@ public function it_finds_canton_by_zipcode()
     }
 
     #[Test]
-    public function it_does_not_find_result_for_not_available_zipcode()
+    public function it_does_not_find_result_for_not_available_zipcode(): void
     {
         $zipcodeSearch = new ZipcodeSearch();
 
@@ -39,7 +39,7 @@ public function it_does_not_find_result_for_not_available_zipcode()
     }
 
     #[Test]
-    public function it_does_not_find_liechtenstein_zipcodes()
+    public function it_does_not_find_liechtenstein_zipcodes(): void
     {
         $zipcodeSearch = new ZipcodeSearch();