diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index f33285d..977cb6a 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -38,7 +38,5 @@ jobs:
         run: php -v
       - name: Install Dependencies
         run: composer install -q --no-ansi --no-interaction --no-scripts --no-suggest --no-progress --prefer-dist
-      - name: Downloading
-        run: wget https://github.com/vimeo/psalm/releases/download/5.9.0/psalm.phar
       - name: Typechecking
-        run: php psalm.phar
+        run: php ./vendor/bin/psalm
diff --git a/composer.json b/composer.json
index 868eb35..ce9fc62 100644
--- a/composer.json
+++ b/composer.json
@@ -6,16 +6,17 @@
     "description": "A PHP client library for 'Vault by HashiCorp'",
     "require": {
         "ext-json": "*",
-        "guzzlehttp/psr7": "^2.4.4",
-        "php": "^7.0 || ^8.0",
-        "php-http/httplug": ">=1.1.0"
+        "guzzlehttp/psr7": "2.6.2",
+        "php": "^7.2.5 || ^8.0",
+        "php-http/httplug": "2.4.0"
     },
     "suggest": {
         "php-http/curl-client": "CURL Client Adapter",
         "tuupola/http-factory": "HTTP Factory"
     },
     "require-dev": {
-        "phpunit/phpunit": ">=5.0.0"
+        "phpunit/phpunit": "9.6.19",
+        "vimeo/psalm": "5.23.1"
     },
     "authors": [
         {
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 18ded4c..7b8d966 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,13 +1,9 @@
 <?xml version="1.0" encoding="utf-8"?>
-<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" bootstrap="./tests/bootstrap.php" xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/11.1/phpunit.xsd" cacheDirectory=".phpunit.cache">
+<phpunit bootstrap="./tests/bootstrap.php" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:noNamespaceSchemaLocation="vendor/phpunit/phpunit/phpunit.xsd">
   <testsuites>
     <testsuite name="The project's test suite">
       <directory>./tests</directory>
     </testsuite>
   </testsuites>
-  <source>
-    <include>
-      <directory suffix=".php">./src/</directory>
-    </include>
-  </source>
 </phpunit>
diff --git a/src/VaultPHP/Authentication/Provider/AppRole.php b/src/VaultPHP/Authentication/Provider/AppRole.php
index 7b90cd6..cc7e893 100644
--- a/src/VaultPHP/Authentication/Provider/AppRole.php
+++ b/src/VaultPHP/Authentication/Provider/AppRole.php
@@ -28,10 +28,10 @@ class AppRole extends AbstractAuthenticationProvider
 
     /**
      * AppRole constructor.
-     * @param $roleId
-     * @param $secretId
+     * @param string $roleId
+     * @param string $secretId
      */
-    public function __construct($roleId, $secretId)
+    public function __construct(string $roleId, string $secretId)
     {
         $this->roleId = $roleId;
         $this->secretId= $secretId;
diff --git a/src/VaultPHP/Response/BulkEndpointResponse.php b/src/VaultPHP/Response/BulkEndpointResponse.php
index c8b040f..c842c03 100644
--- a/src/VaultPHP/Response/BulkEndpointResponse.php
+++ b/src/VaultPHP/Response/BulkEndpointResponse.php
@@ -45,7 +45,8 @@ public function hasErrors() {
     /**
      * @return array
      */
-    public function getBatchResults() {
+    public function getBatchResults(): array
+    {
         return $this->batch_results;
     }
 
diff --git a/src/VaultPHP/Response/EndpointResponse.php b/src/VaultPHP/Response/EndpointResponse.php
index 67c6e23..cd32bf5 100644
--- a/src/VaultPHP/Response/EndpointResponse.php
+++ b/src/VaultPHP/Response/EndpointResponse.php
@@ -28,7 +28,8 @@ final public function __construct($data = [], $meta = [])
      * @param $response
      * @return array
      */
-    protected static function getResponseContent(ResponseInterface $response) {
+    protected static function getResponseContent(ResponseInterface $response): array
+    {
         $responseBody = $response->getBody();
         $responseBody->rewind();
         $responseBodyContents = $responseBody->getContents();
diff --git a/src/VaultPHP/SecretEngines/Engines/Transit/Transit.php b/src/VaultPHP/SecretEngines/Engines/Transit/Transit.php
index a40fb64..9d9749a 100644
--- a/src/VaultPHP/SecretEngines/Engines/Transit/Transit.php
+++ b/src/VaultPHP/SecretEngines/Engines/Transit/Transit.php
@@ -29,8 +29,15 @@
  */
 final class Transit extends AbstractSecretEngine
 {
-    private string $APIPath = 'transit';
+    /**
+     * @var string
+     */
+    private $APIPath = 'transit';
 
+    /**
+     * @param string $path
+     * @return void
+     */
     public function setAPIPath(string $path)
     {
         $this->APIPath = $path;
diff --git a/src/VaultPHP/VaultClient.php b/src/VaultPHP/VaultClient.php
index 38061ff..48b645a 100644
--- a/src/VaultPHP/VaultClient.php
+++ b/src/VaultPHP/VaultClient.php
@@ -3,7 +3,7 @@
 namespace VaultPHP;
 
 use GuzzleHttp\Psr7\Request;
-use Http\Client\HttpClient;
+use Psr\Http\Client\ClientInterface;
 use Psr\Http\Message\RequestInterface;
 use Psr\Http\Message\ResponseInterface;
 use VaultPHP\Authentication\AuthenticationMetaData;
@@ -27,7 +27,7 @@ class VaultClient
     /** @var string */
     private $apiHost;
 
-    /** @var HttpClient */
+    /** @var ClientInterface */
     private $httpClient;
 
     /** @var AuthenticationProviderInterface */
@@ -38,12 +38,12 @@ class VaultClient
 
     /**
      * VaultClient constructor.
-     * @param HttpClient $httpClient
+     * @param ClientInterface $httpClient
      * @param AuthenticationProviderInterface $authProvider
      * @param string $apiHost
      */
     public function __construct(
-        HttpClient $httpClient,
+        ClientInterface $httpClient,
         AuthenticationProviderInterface $authProvider,
         $apiHost
     )