diff --git a/.editorconfig b/.editorconfig
new file mode 100644
index 0000000..01909e6
--- /dev/null
+++ b/.editorconfig
@@ -0,0 +1,13 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_size = 4
+indent_style = space
+insert_final_newline = true
+tab_width = 4
+trim_trailing_whitespace = true
+
+[.github/workflows/*.yml]
+indent_size = 2
diff --git a/.gitattributes b/.gitattributes
index 5091d75..1c61dac 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -1,6 +1,8 @@
+/.editorconfig export-ignore
 /.gitattributes export-ignore
 /.github export-ignore
 /.gitignore export-ignore
 /phpunit.xml.dist export-ignore
 /phpunit.http_client.xml export-ignore
+/phpstan*.neon export-ignore
 /tests export-ignore
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 2738dba..10b42c5 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -10,6 +10,29 @@ defaults:
     shell: bash
 
 jobs:
+  check_composer:
+    name: Check composer.json
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: shivammathur/setup-php@v2
+        with:
+          coverage: none
+          php-version: '8.2'
+      - run: composer validate --strict --no-check-lock
+
+  static_analysis:
+    name: Static analysis
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: shivammathur/setup-php@v2
+        with:
+          coverage: none
+          php-version: '8.2'
+      - name: Install dependencies
+        run: composer update --ansi --no-progress --prefer-dist --no-interaction
+      - run: vendor/bin/phpstan analyze
 
   tests:
     name: Tests on PHP ${{ matrix.php }} with ${{ matrix.implementation }}${{ matrix.name_suffix }}
diff --git a/composer.json b/composer.json
index 8ad1513..9ca8614 100644
--- a/composer.json
+++ b/composer.json
@@ -16,6 +16,7 @@
 
     "require": {
         "php": ">=7.2",
+        "ext-dom": "*",
         "behat/mink": "^1.9.0@dev",
         "symfony/browser-kit": "^4.4 || ^5.0 || ^6.0",
         "symfony/dom-crawler": "^4.4 || ^5.0 || ^6.0"
@@ -23,11 +24,13 @@
 
     "require-dev": {
         "mink/driver-testsuite": "dev-master",
+        "phpstan/phpstan": "^1.10",
+        "phpstan/phpstan-phpunit": "^1.3",
+        "phpunit/phpunit": "^8.5 || ^9.5",
         "symfony/error-handler": "^4.4 || ^5.0 || ^6.0",
         "symfony/http-client": "^4.4 || ^5.0 || ^6.0",
         "symfony/http-kernel": "^4.4 || ^5.0 || ^6.0",
         "symfony/mime": "^4.4 || ^5.0 || ^6.0",
-        "phpunit/phpunit": "^8.5 || ^9.5",
         "yoast/phpunit-polyfills": "^1.0"
     },
 
diff --git a/phpstan.dist.neon b/phpstan.dist.neon
new file mode 100644
index 0000000..f7cbf4c
--- /dev/null
+++ b/phpstan.dist.neon
@@ -0,0 +1,12 @@
+parameters:
+    level: 8
+    paths:
+        - src
+        - tests
+    checkMissingIterableValueType: false
+    ignoreErrors:
+        - '#^Method Behat\\Mink\\Tests\\Driver\\Custom\\[^:]+Test(Case)?\:\:test\w*\(\) has no return type specified\.$#'
+
+includes:
+    - vendor/phpstan/phpstan-phpunit/extension.neon
+    - vendor/phpstan/phpstan-phpunit/rules.neon
diff --git a/src/BrowserKitDriver.php b/src/BrowserKitDriver.php
index 9f887e1..a216dff 100644
--- a/src/BrowserKitDriver.php
+++ b/src/BrowserKitDriver.php
@@ -13,7 +13,6 @@
 use Behat\Mink\Exception\DriverException;
 use Behat\Mink\Exception\UnsupportedDriverActionException;
 use Symfony\Component\BrowserKit\AbstractBrowser;
-use Symfony\Component\BrowserKit\Client;
 use Symfony\Component\BrowserKit\Cookie;
 use Symfony\Component\BrowserKit\Exception\BadMethodCallException;
 use Symfony\Component\BrowserKit\Response;
@@ -32,13 +31,22 @@
  */
 class BrowserKitDriver extends CoreDriver
 {
+    /**
+     * @var AbstractBrowser
+     */
     private $client;
 
     /**
-     * @var Form[]
+     * @var array<string, Form>
      */
     private $forms = array();
+    /**
+     * @var array<string, string>
+     */
     private $serverParameters = array();
+    /**
+     * @var bool
+     */
     private $started = false;
 
     /**
@@ -46,13 +54,17 @@ class BrowserKitDriver extends CoreDriver
      *
      * @param string|null $baseUrl Base URL for HttpKernel clients
      */
-    public function __construct(AbstractBrowser $client, $baseUrl = null)
+    public function __construct(AbstractBrowser $client, ?string $baseUrl = null)
     {
         $this->client = $client;
         $this->client->followRedirects(true);
 
         if ($baseUrl !== null && $client instanceof HttpKernelBrowser) {
-            $client->setServerParameter('SCRIPT_FILENAME', parse_url($baseUrl, PHP_URL_PATH));
+            $basePath = parse_url($baseUrl, PHP_URL_PATH);
+
+            if (\is_string($basePath)) {
+                $client->setServerParameter('SCRIPT_FILENAME', $basePath);
+            }
         }
     }
 
@@ -219,7 +231,7 @@ public function setCookie($name, $value = null)
      *
      * @param string $name Cookie name.
      */
-    private function deleteCookie($name)
+    private function deleteCookie(string $name): void
     {
         $path = $this->getCookiePath();
         $jar = $this->client->getCookieJar();
@@ -235,13 +247,15 @@ private function deleteCookie($name)
 
     /**
      * Returns current cookie path.
-     *
-     * @return string
      */
-    private function getCookiePath()
+    private function getCookiePath(): string
     {
         $path = parse_url($this->getCurrentUrl(), PHP_URL_PATH);
 
+        if ($path === null || $path === false || $path === '') {
+            $path = '/';
+        }
+
         if ('\\' === DIRECTORY_SEPARATOR) {
             $path = str_replace('\\', '/', $path);
         }
@@ -394,7 +408,18 @@ public function getValue($xpath)
      */
     public function setValue($xpath, $value)
     {
-        $this->getFormField($xpath)->setValue($value);
+        $field = $this->getFormField($xpath);
+
+        if ($field instanceof ChoiceFormField) {
+            $field->setValue($value);
+            return;
+        }
+
+        if (!\is_string($value) && null !== $value) {
+            throw new DriverException('Textual form fields don\'t support array or boolean values');
+        }
+
+        $field->setValue($value);
     }
 
     /**
@@ -554,6 +579,7 @@ protected function prepareUrl($url)
      * @return FormField
      *
      * @throws DriverException
+     * @throws \InvalidArgumentException when the field does not exist in the BrowserKit form
      */
     protected function getFormField($xpath)
     {
@@ -568,7 +594,11 @@ protected function getFormField($xpath)
         }
 
         if (is_array($this->forms[$formId][$fieldName])) {
-            return $this->forms[$formId][$fieldName][$this->getFieldPosition($fieldNode)];
+            $positionField = $this->forms[$formId][$fieldName][$this->getFieldPosition($fieldNode)];
+
+            \assert($positionField instanceof FormField);
+
+            return $positionField;
         }
 
         return $this->forms[$formId][$fieldName];
@@ -605,6 +635,7 @@ private function getFormNode(\DOMElement $element)
     {
         if ($element->hasAttribute('form')) {
             $formId = $element->getAttribute('form');
+            \assert($element->ownerDocument !== null);
             $formNode = $element->ownerDocument->getElementById($formId);
 
             if (null === $formNode || 'form' !== $formNode->nodeName) {
@@ -623,6 +654,8 @@ private function getFormNode(\DOMElement $element)
             }
         } while ('form' !== $formNode->nodeName);
 
+        \assert($formNode instanceof \DOMElement);
+
         return $formNode;
     }
 
@@ -633,11 +666,9 @@ private function getFormNode(\DOMElement $element)
      * When multiple fields have the same name (checkboxes for instance), it will return
      * an array of elements in the order they appear in the DOM.
      *
-     * @param \DOMElement $fieldNode
-     *
-     * @return integer
+     * @throws DriverException
      */
-    private function getFieldPosition(\DOMElement $fieldNode)
+    private function getFieldPosition(\DOMElement $fieldNode): int
     {
         $elements = $this->getCrawler()->filterXPath('//*[@name=\''.$fieldNode->getAttribute('name').'\']');
 
@@ -655,7 +686,7 @@ private function getFieldPosition(\DOMElement $fieldNode)
         return 0;
     }
 
-    private function submit(Form $form)
+    private function submit(Form $form): void
     {
         $formId = $this->getFormNodeId($form->getFormNode());
 
@@ -675,21 +706,14 @@ private function submit(Form $form)
         $this->forms = array();
     }
 
-    private function resetForm(\DOMElement $fieldNode)
+    private function resetForm(\DOMElement $fieldNode): void
     {
         $formNode = $this->getFormNode($fieldNode);
         $formId = $this->getFormNodeId($formNode);
         unset($this->forms[$formId]);
     }
 
-    /**
-     * Determines if a node can submit a form.
-     *
-     * @param \DOMElement $node Node.
-     *
-     * @return boolean
-     */
-    private function canSubmitForm(\DOMElement $node)
+    private function canSubmitForm(\DOMElement $node): bool
     {
         $type = $node->hasAttribute('type') ? $node->getAttribute('type') : null;
 
@@ -700,14 +724,7 @@ private function canSubmitForm(\DOMElement $node)
         return 'button' === $node->nodeName && (null === $type || 'submit' === $type);
     }
 
-    /**
-     * Determines if a node can reset a form.
-     *
-     * @param \DOMElement $node Node.
-     *
-     * @return boolean
-     */
-    private function canResetForm(\DOMElement $node)
+    private function canResetForm(\DOMElement $node): bool
     {
         $type = $node->hasAttribute('type') ? $node->getAttribute('type') : null;
 
@@ -754,7 +771,7 @@ private function getOptionValue(\DOMElement $option)
      * @param Form $to   merging target
      * @param Form $from merging source
      */
-    private function mergeForms(Form $to, Form $from)
+    private function mergeForms(Form $to, Form $from): void
     {
         foreach ($from->all() as $name => $field) {
             $fieldReflection = new \ReflectionObject($field);
@@ -768,7 +785,11 @@ private function mergeForms(Form $to, Form $from)
                 in_array($nodeReflection->getValue($field)->getAttribute('type'), array('submit', 'button', 'image'), true);
 
             if (!$isIgnoredField) {
-                $valueReflection->setValue($to[$name], $valueReflection->getValue($field));
+                $targetField = $to[$name];
+
+                \assert($targetField instanceof FormField);
+
+                $valueReflection->setValue($targetField, $valueReflection->getValue($field));
             }
         }
     }
@@ -776,17 +797,15 @@ private function mergeForms(Form $to, Form $from)
     /**
      * Returns DOMElement from crawler instance.
      *
-     * @param Crawler $crawler
-     *
-     * @return \DOMElement
-     *
      * @throws DriverException when the node does not exist
      */
-    private function getCrawlerNode(Crawler $crawler)
+    private function getCrawlerNode(Crawler $crawler): \DOMElement
     {
         $node = $crawler->getNode(0);
 
         if (null !== $node) {
+            \assert($node instanceof \DOMElement);
+
             return $node;
         }
 
diff --git a/tests/AbstractBrowserKitConfig.php b/tests/AbstractBrowserKitConfig.php
index 1003eed..6f096b0 100644
--- a/tests/AbstractBrowserKitConfig.php
+++ b/tests/AbstractBrowserKitConfig.php
@@ -7,6 +7,13 @@
 
 abstract class AbstractBrowserKitConfig extends AbstractConfig
 {
+    final public function __construct()
+    {
+    }
+
+    /**
+     * @return static
+     */
     public static function getInstance()
     {
         return new static();
@@ -25,7 +32,7 @@ public function skipMessage($testCase, $test): ?string
         return parent::skipMessage($testCase, $test);
     }
 
-    protected function supportsJs()
+    protected function supportsJs(): bool
     {
         return false;
     }
diff --git a/tests/Custom/ErrorHandlingTest.php b/tests/Custom/ErrorHandlingTest.php
index aa6dbad..19ba56d 100644
--- a/tests/Custom/ErrorHandlingTest.php
+++ b/tests/Custom/ErrorHandlingTest.php
@@ -20,7 +20,7 @@ class ErrorHandlingTest extends TestCase
     /**
      * @before
      */
-    protected function prepareClient()
+    protected function prepareClient(): void
     {
         $this->client = new TestClient();
     }
@@ -154,7 +154,7 @@ public function testClickOnUnsupportedElement()
         $driver->click('//div');
     }
 
-    private function getDriver()
+    private function getDriver(): BrowserKitDriver
     {
         return new BrowserKitDriver($this->client);
     }
@@ -162,19 +162,19 @@ private function getDriver()
 
 class TestClient extends AbstractBrowser
 {
+    /**
+     * @var Response|null
+     */
     protected $nextResponse = null;
-    protected $nextScript = null;
 
-    public function setNextResponse(Response $response)
+    public function setNextResponse(Response $response): void
     {
         $this->nextResponse = $response;
     }
 
-    public function setNextScript($script)
-    {
-        $this->nextScript = $script;
-    }
-
+    /**
+     * @param object $request
+     */
     protected function doRequest($request): object
     {
         if (null === $this->nextResponse) {
diff --git a/tests/HttpClientBrowserKitConfig.php b/tests/HttpClientBrowserKitConfig.php
index 900d0c6..4b6576f 100644
--- a/tests/HttpClientBrowserKitConfig.php
+++ b/tests/HttpClientBrowserKitConfig.php
@@ -3,11 +3,12 @@
 namespace Behat\Mink\Tests\Driver;
 
 use Behat\Mink\Driver\BrowserKitDriver;
+use Behat\Mink\Driver\DriverInterface;
 use Symfony\Component\BrowserKit\HttpBrowser;
 
 class HttpClientBrowserKitConfig extends AbstractBrowserKitConfig
 {
-    public function createDriver()
+    public function createDriver(): DriverInterface
     {
         return new BrowserKitDriver(new HttpBrowser());
     }
diff --git a/tests/HttpKernelBrowserKitConfig.php b/tests/HttpKernelBrowserKitConfig.php
index 9b89a3d..13e2e33 100644
--- a/tests/HttpKernelBrowserKitConfig.php
+++ b/tests/HttpKernelBrowserKitConfig.php
@@ -3,25 +3,20 @@
 namespace Behat\Mink\Tests\Driver;
 
 use Behat\Mink\Driver\BrowserKitDriver;
+use Behat\Mink\Driver\DriverInterface;
 use Behat\Mink\Tests\Driver\Util\FixturesKernel;
 use Symfony\Component\HttpKernel\HttpKernelBrowser;
 
 class HttpKernelBrowserKitConfig extends AbstractBrowserKitConfig
 {
-    /**
-     * {@inheritdoc}
-     */
-    public function createDriver()
+    public function createDriver(): DriverInterface
     {
         $client = new HttpKernelBrowser(new FixturesKernel());
 
         return new BrowserKitDriver($client);
     }
 
-    /**
-     * {@inheritdoc}
-     */
-    public function getWebFixturesUrl()
+    public function getWebFixturesUrl(): string
     {
         return 'http://localhost';
     }