diff --git a/.github/workflows/behat.yml b/.github/workflows/behat.yml
index 571e0c7..b508c99 100644
--- a/.github/workflows/behat.yml
+++ b/.github/workflows/behat.yml
@@ -32,21 +32,11 @@ jobs:
     strategy:
       matrix:
         os: [ ubuntu-latest ]
-        php: [ '7.4' ]
+        php: [ '8.1' ]
         wordpress: [ 'latest' ]
         glotpress: [ 'latest' ]
         experimental: [ false ]
         include:
-          - os: ubuntu-latest
-            php: '8.0'
-            wordpress: 'latest'
-            glotpress: 'latest'
-            experimental: false
-          - os: ubuntu-latest
-            php: '8.1'
-            wordpress: 'latest'
-            glotpress: 'latest'
-            experimental: false
           - os: ubuntu-latest
             php: '8.2'
             wordpress: 'latest'
@@ -63,6 +53,11 @@ jobs:
             wordpress: 'nightly'
             glotpress: 'develop'
             experimental: true
+          - os: ubuntu-latest
+            php: '8.4'
+            wordpress: 'nightly'
+            glotpress: 'develop'
+            experimental: true
 
     steps:
       - name: Check out Git repository
diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index 331f30e..481536a 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -18,7 +18,7 @@ jobs:
       - name: Set up PHP
         uses: shivammathur/setup-php@v2
         with:
-          php-version: "7.4"
+          php-version: latest
           coverage: none
           tools: composer, cs2pr
 
diff --git a/.github/workflows/phpunit.yml b/.github/workflows/phpunit.yml
index eaf145a..56a08e5 100644
--- a/.github/workflows/phpunit.yml
+++ b/.github/workflows/phpunit.yml
@@ -28,21 +28,11 @@ jobs:
     strategy:
       matrix:
         os: [ ubuntu-latest ]
-        php: [ '7.4' ]
+        php: [ '8.1' ]
         wordpress: [ 'latest' ]
         glotpress: [ 'latest' ]
         experimental: [ false ]
         include:
-          - os: ubuntu-latest
-            php: '8.0'
-            wordpress: 'latest'
-            glotpress: 'latest'
-            experimental: false
-          - os: ubuntu-latest
-            php: '8.1'
-            wordpress: 'latest'
-            glotpress: 'latest'
-            experimental: false
           - os: ubuntu-latest
             php: '8.2'
             wordpress: 'latest'
@@ -59,6 +49,11 @@ jobs:
             wordpress: 'nightly'
             glotpress: 'develop'
             experimental: true
+          - os: ubuntu-latest
+            php: '8.4'
+            wordpress: 'nightly'
+            glotpress: 'develop'
+            experimental: true
 
     steps:
       - name: Check out Git repository
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 62ce774..6d9a92f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,7 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 * Require GlotPress 4.0. [#270]
-* Require at least PHP 7.4. [#270]
+* Require at least PHP 8.1. [#270]
 
 ### Fixed
 * Pass correct parameter for translation set in `traduttore.generate_zip_delay` filter. [#236]
diff --git a/composer.json b/composer.json
index fff916e..8d508c4 100644
--- a/composer.json
+++ b/composer.json
@@ -35,7 +35,7 @@
     "issues": "https://github.com/wearerequired/traduttore/issues"
   },
   "require": {
-    "php": ">=7.4",
+    "php": ">=8.1",
     "ext-json": "*",
     "ext-zip": "*",
     "wearerequired/traduttore-registry": "^2.0"
diff --git a/inc/Plugin.php b/inc/Plugin.php
index d9dbc0b..8babe7a 100644
--- a/inc/Plugin.php
+++ b/inc/Plugin.php
@@ -419,7 +419,7 @@ public function incoming_webhook_permission_callback( WP_REST_Request $request )
 		 * @param \Required\Traduttore\WebhookHandler|null $handler The current webhook handler if found.
 		 * @param \WP_REST_Request                         $request The current request.
 		 */
-		return apply_filters( 'traduttore.incoming_webhook_permission_callback', (bool) $result, $handler, $request );
+		return apply_filters( 'traduttore.incoming_webhook_permission_callback', $result, $handler, $request );
 	}
 
 	/**
diff --git a/inc/WebhookHandler.php b/inc/WebhookHandler.php
index b75b2ee..055eb00 100644
--- a/inc/WebhookHandler.php
+++ b/inc/WebhookHandler.php
@@ -33,7 +33,7 @@ public function __construct( WP_REST_Request $request );
 	 *
 	 * @return bool True if permission is granted, false otherwise.
 	 */
-	public function permission_callback(): ?bool;
+	public function permission_callback(): bool;
 
 	/**
 	 * Callback for incoming webhooks.
diff --git a/inc/WebhookHandler/Bitbucket.php b/inc/WebhookHandler/Bitbucket.php
index 33fec60..9d5c252 100644
--- a/inc/WebhookHandler/Bitbucket.php
+++ b/inc/WebhookHandler/Bitbucket.php
@@ -27,7 +27,7 @@ class Bitbucket extends Base {
 	 *
 	 * @return bool True if permission is granted, false otherwise.
 	 */
-	public function permission_callback(): ?bool {
+	public function permission_callback(): bool {
 		$event_name = $this->request->get_header( 'x-event-key' );
 
 		if ( 'repo:push' !== $event_name ) {
diff --git a/inc/WebhookHandler/GitHub.php b/inc/WebhookHandler/GitHub.php
index 7d548e4..6e5db54 100644
--- a/inc/WebhookHandler/GitHub.php
+++ b/inc/WebhookHandler/GitHub.php
@@ -27,7 +27,7 @@ class GitHub extends Base {
 	 *
 	 * @return bool True if permission is granted, false otherwise.
 	 */
-	public function permission_callback(): ?bool {
+	public function permission_callback(): bool {
 		$event_name = $this->request->get_header( 'x-github-event' );
 
 		if ( 'ping' === $event_name ) {
diff --git a/inc/WebhookHandler/GitLab.php b/inc/WebhookHandler/GitLab.php
index 69c65ee..4ef4780 100644
--- a/inc/WebhookHandler/GitLab.php
+++ b/inc/WebhookHandler/GitLab.php
@@ -27,7 +27,7 @@ class GitLab extends Base {
 	 *
 	 * @return bool True if permission is granted, false otherwise.
 	 */
-	public function permission_callback(): ?bool {
+	public function permission_callback(): bool {
 		$event_name = $this->request->get_header( 'x-gitlab-event' );
 
 		if ( 'Push Hook' !== $event_name ) {
diff --git a/tests/phpunit/tests/Repository/Bitbucket.php b/tests/phpunit/tests/Repository/Bitbucket.php
index 7213401..9cfdc3f 100644
--- a/tests/phpunit/tests/Repository/Bitbucket.php
+++ b/tests/phpunit/tests/Repository/Bitbucket.php
@@ -88,7 +88,7 @@ public function test_get_name(): void {
 	 * @param string $url     The request URL.
 	 * @return array{response: array{ code: int }, body: string}|false Response data.
 	 */
-	public function mock_repository_visibility_request( false $preempt, mixed $r, string $url ): array|false {
+	public function mock_repository_visibility_request( bool $preempt, mixed $r, string $url ): array|false {
 		if ( BitbucketRepository::API_BASE . '/repositories/wearerequired/traduttore' === $url ) {
 			++$this->http_request_count;
 
diff --git a/tests/phpunit/tests/Repository/GitHub.php b/tests/phpunit/tests/Repository/GitHub.php
index eb14bf2..41bd894 100644
--- a/tests/phpunit/tests/Repository/GitHub.php
+++ b/tests/phpunit/tests/Repository/GitHub.php
@@ -103,7 +103,7 @@ public function test_get_name(): void {
 	 * @param string $url     The request URL.
 	 * @return array{response: array{ code: int }, body: string}|false Response data.
 	 */
-	public function mock_repository_visibility_request( false $preempt, mixed $r, string $url ): array|false {
+	public function mock_repository_visibility_request( bool $preempt, mixed $r, string $url ): array|false {
 		if ( GitHubRepository::API_BASE . '/repos/wearerequired/traduttore' === $url ) {
 			++$this->http_request_count;
 
diff --git a/tests/phpunit/tests/Repository/GitLab.php b/tests/phpunit/tests/Repository/GitLab.php
index 0e0eed6..5d0865f 100644
--- a/tests/phpunit/tests/Repository/GitLab.php
+++ b/tests/phpunit/tests/Repository/GitLab.php
@@ -102,7 +102,7 @@ public function test_get_host(): void {
 	 * @param string $url     The request URL.
 	 * @return array{response: array{ code: int }, body: string}|false Response data.
 	 */
-	public function mock_repository_visibility_request( false $preempt, mixed $r, string $url ): array|false {
+	public function mock_repository_visibility_request( bool $preempt, mixed $r, string $url ): array|false {
 		if ( GitLabRepository::API_BASE . '/projects/wearerequired%2Ftraduttore' === $url ) {
 			++$this->http_request_count;
 
diff --git a/traduttore.php b/traduttore.php
index 5b76ace..b9cc973 100644
--- a/traduttore.php
+++ b/traduttore.php
@@ -11,7 +11,8 @@
  * Text Domain: traduttore
  * Domain Path: /languages
  * Update URI:  false
- * Requires PHP: 7.4
+ * Requires PHP: 8.1
+ * Requires Plugins: glotpress
  *
  * Copyright (c) 2017-2022 required (email: info@required.ch)
  *