diff --git a/typo3/sysext/frontend/Classes/Controller/ErrorController.php b/typo3/sysext/frontend/Classes/Controller/ErrorController.php
index 669b6a97e4911b58f14aa2ca4bebb3efff8fa988..8b8aea124bf9ec9d93ff99e1450be520dfaa799e 100644
--- a/typo3/sysext/frontend/Classes/Controller/ErrorController.php
+++ b/typo3/sysext/frontend/Classes/Controller/ErrorController.php
@@ -144,7 +144,7 @@ class ErrorController
         $response = null;
         $content = '';
         // Simply boolean; Just shows TYPO3 error page with reason:
-        if (gettype($errorHandler) === 'boolean' || strtolower($errorHandler) === 'true' || (string)$errorHandler === '1') {
+        if (is_bool($errorHandler) || strtolower($errorHandler) === 'true' || (string)$errorHandler === '1') {
             $content = GeneralUtility::makeInstance(ErrorPageController::class)->errorAction(
                 'Page Not Found',
                 'The page did not exist or was inaccessible.' . ($reason ? ' Reason: ' . $reason : '')
diff --git a/typo3/sysext/frontend/Classes/Controller/TypoScriptFrontendController.php b/typo3/sysext/frontend/Classes/Controller/TypoScriptFrontendController.php
index 9160cc9f60ded4413f173b76b3bba0c3ebb6349b..30340ca9569aa7d4a1d9aa9a22a0333a58338545 100644
--- a/typo3/sysext/frontend/Classes/Controller/TypoScriptFrontendController.php
+++ b/typo3/sysext/frontend/Classes/Controller/TypoScriptFrontendController.php
@@ -1975,7 +1975,7 @@ class TypoScriptFrontendController implements LoggerAwareInterface
         }
         // Create response:
         // Simply boolean; Just shows TYPO3 error page with reason:
-        if (strtolower($code) === 'true' || (string)$code === '1' || gettype($code) === 'boolean') {
+        if (strtolower($code) === 'true' || (string)$code === '1' || is_bool($code)) {
             echo GeneralUtility::makeInstance(ErrorPageController::class)->errorAction(
                 'Page Not Found',
                 'The page did not exist or was inaccessible.' . ($reason ? ' Reason: ' . $reason : '')
diff --git a/typo3/sysext/saltedpasswords/Tests/Unit/Salt/Argon2iSaltTest.php b/typo3/sysext/saltedpasswords/Tests/Unit/Salt/Argon2iSaltTest.php
index 576851735a9117b24fa2f48141a825edc0d87274..9debc7cf1b7605cfddb80209c3b1d5cb6cd6fce4 100644
--- a/typo3/sysext/saltedpasswords/Tests/Unit/Salt/Argon2iSaltTest.php
+++ b/typo3/sysext/saltedpasswords/Tests/Unit/Salt/Argon2iSaltTest.php
@@ -101,7 +101,7 @@ class Argon2iSaltTest extends UnitTestCase
     {
         $hash = $this->subject->getHashedPassword('password');
         $this->assertNotNull($hash);
-        $this->assertEquals('string', gettype($hash));
+        $this->assertTrue(is_string($hash));
     }
 
     /**
diff --git a/typo3/sysext/saltedpasswords/Tests/Unit/Salt/BcryptSaltTest.php b/typo3/sysext/saltedpasswords/Tests/Unit/Salt/BcryptSaltTest.php
index c82b5b185caaedc6a0b6d9589566830e4d46f6bf..3153ea6e8a9b440d9509b5377a969755942c6bc0 100644
--- a/typo3/sysext/saltedpasswords/Tests/Unit/Salt/BcryptSaltTest.php
+++ b/typo3/sysext/saltedpasswords/Tests/Unit/Salt/BcryptSaltTest.php
@@ -77,7 +77,7 @@ class BcryptSaltTest extends UnitTestCase
     {
         $hash = $this->subject->getHashedPassword('password');
         $this->assertNotNull($hash);
-        $this->assertEquals('string', gettype($hash));
+        $this->assertTrue(is_string($hash));
     }
 
     /**