diff --git a/phpstan.dist.neon b/phpstan.dist.neon
index 7b42960..f0dc8e8 100644
--- a/phpstan.dist.neon
+++ b/phpstan.dist.neon
@@ -3,7 +3,7 @@ includes:
 	- vendor/phpstan/phpstan-phpunit/rules.neon
 
 parameters:
-	level: 8
+	level: 9
 	paths:
 		- src
 		- tests
diff --git a/src/WebdriverClassicDriver.php b/src/WebdriverClassicDriver.php
index da24eae..47c18f7 100644
--- a/src/WebdriverClassicDriver.php
+++ b/src/WebdriverClassicDriver.php
@@ -280,7 +280,7 @@ public function getWindowNames(): array
 
     public function getWindowName(): string
     {
-        $name = (string)$this->evaluateScript('window.name');
+        $name = $this->getAsString($this->evaluateScript('window.name'), 'Window name');
 
         if ($name === '') {
             $name = self::W3C_WINDOW_HANDLE_PREFIX . $this->getWebDriver()->getWindowHandle();
@@ -317,7 +317,7 @@ public function getText(
         return trim(str_replace(
             ["\r\n", "\r", "\n", "\xc2\xa0"],
             ' ',
-            $this->getElementDomProperty($this->findElement($xpath), 'innerText')
+            $this->getAsString($this->getElementDomProperty($this->findElement($xpath), 'innerText'), 'The element\'s innerText')
         ));
     }
 
@@ -325,14 +325,14 @@ public function getHtml(
         #[Language('XPath')]
         string $xpath
     ): string {
-        return $this->getElementDomProperty($this->findElement($xpath), 'innerHTML');
+        return $this->getAsString($this->getElementDomProperty($this->findElement($xpath), 'innerHTML'), 'The element\'s innerHTML');
     }
 
     public function getOuterHtml(
         #[Language('XPath')]
         string $xpath
     ): string {
-        return $this->getElementDomProperty($this->findElement($xpath), 'outerHTML');
+        return $this->getAsString($this->getElementDomProperty($this->findElement($xpath), 'outerHTML'), 'The element\'s outerHTML');
     }
 
     public function getAttribute(
@@ -344,7 +344,8 @@ public function getAttribute(
         // so we cannot use webdriver api for this. See also: https://w3c.github.io/webdriver/#dfn-get-element-attribute
         $escapedName = $this->jsonEncode($name, 'get attribute', 'attribute name');
         $script = "return arguments[0].getAttribute($escapedName)";
-        return $this->executeJsOnXpath($xpath, $script);
+        $result = $this->executeJsOnXpath($xpath, $script);
+        return $result === null ? null : $this->getAsString($result, "The element's $name attribute");
     }
 
     /**
@@ -412,7 +413,7 @@ public function setValue(
                     if (is_array($value)) {
                         $this->deselectAllOptions($element);
                         foreach ($value as $option) {
-                            $this->selectOptionOnElement($element, $option, true);
+                            $this->selectOptionOnElement($element, $this->getAsString($option, 'Option value'), true);
                         }
                         return;
                     }
@@ -941,12 +942,13 @@ private function charToSynOptions($char, ?string $modifier = null): string
      * Executes JS on a given element - pass in a js script string and argument[0] will
      * be replaced with a reference to the result of the $xpath query
      *
-     * @param string $xpath the xpath to search with
-     * @param string $script the script to execute
+     * Example:
+     * ```
+     * $this->executeJsOnXpath($xpath, 'return argument[0].childNodes.length');
+     * ```
      *
      * @return mixed
      * @throws DriverException
-     * @example $this->executeJsOnXpath($xpath, 'return argument[0].childNodes.length');
      */
     private function executeJsOnXpath(
         #[Language('XPath')]
@@ -960,11 +962,13 @@ private function executeJsOnXpath(
     /**
      * Executes JS on a given element - pass in a js script string and argument[0] will contain a reference to the element
      *
-     * @param RemoteWebElement $element the webdriver element
-     * @param string $script the script to execute
+     * Example:
+     * ```
+     * $this->executeJsOnElement($element, 'return argument[0].childNodes.length');
+     * ```
+     *
      * @return mixed
      * @throws DriverException
-     * @example $this->executeJsOnXpath($xpath, 'return argument[0].childNodes.length');
      */
     private function executeJsOnElement(
         RemoteWebElement $element,
@@ -1257,5 +1261,21 @@ private function getElementDomProperty(RemoteWebElement $element, string $proper
         }
     }
 
+    /**
+     * @param mixed $value
+     * @throws DriverException
+     */
+    private function getAsString($value, string $name): string
+    {
+        if (!is_scalar($value)) {
+            $actualType = gettype($value);
+            throw new DriverException(
+                "$name should be a string or at least a scalar value, but received `$actualType` instead"
+            );
+        }
+
+        return (string)$value;
+    }
+
     // </editor-fold>
 }
diff --git a/tests/Custom/WebDriverTest.php b/tests/Custom/WebDriverTest.php
index 6a778d4..c56eba5 100644
--- a/tests/Custom/WebDriverTest.php
+++ b/tests/Custom/WebDriverTest.php
@@ -3,6 +3,7 @@
 namespace Mink\WebdriverClassicDriver\Tests\Custom;
 
 use Behat\Mink\Exception\DriverException;
+use Facebook\WebDriver\Remote\RemoteWebElement;
 use Mink\WebdriverClassicDriver\Tests\WebDriverMockingTrait;
 use Mink\WebdriverClassicDriver\WebdriverClassicDriver;
 
@@ -69,4 +70,28 @@ public function testClassicDriverCanProvideBrowserName(): void
             $this->driver->getBrowserName()
         );
     }
+
+    public function testThatDriverCatchesUnexpectedAttributeValueType(): void
+    {
+        $mockWebDriver = $this->createMockWebDriver();
+        $mockElement = $this->createMock(RemoteWebElement::class);
+        $mockWebDriver
+            ->expects($this->once())
+            ->method('findElement')
+            ->willReturn($mockElement);
+        $mockWebDriver
+            ->expects($this->once())
+            ->method('executeScript')
+            ->with('return arguments[0].getAttribute("some-attribute")', [$mockElement])
+            ->willReturn(['invalid attribute value']);
+
+        $driver = new WebdriverClassicDriver('fake browser', [], 'example.com', fn() => $mockWebDriver);
+
+        $driver->start();
+
+        $this->expectException(DriverException::class);
+        $this->expectExceptionMessage('The element\'s some-attribute attribute should be a string or at least a scalar value, but received `array` instead');
+
+        $driver->getAttribute('//fake', 'some-attribute');
+    }
 }