diff --git a/.github/setup-extension.sh b/.github/setup-extension.sh
index 9912737..ebc0de1 100644
--- a/.github/setup-extension.sh
+++ b/.github/setup-extension.sh
@@ -10,15 +10,15 @@ NOTESTS="${2}"
 composer update -n --prefer-dist --no-progress
 
 # Prepare extension structure
-mkdir -p ../phpBB3/phpBB/ext/"${EXTNAME}"
+mkdir -p ../phpbb/phpBB/ext/"${EXTNAME}"
 
 # Build extension package
 vendor/bin/phing
 
 # Copy extension files and directories
-cp -a build/package/"${EXTNAME}"/* ../phpBB3/phpBB/ext/"${EXTNAME}"/
+cp -a build/package/"${EXTNAME}"/* ../phpbb/phpBB/ext/"${EXTNAME}"/
 
 # Add required files for tests
 if [[ "${NOTESTS}" != 1 ]]; then
-	cp -a {phpunit.xml.dist,tests/} ../phpBB3/phpBB/ext/"${EXTNAME}"/
+	cp -a {phpunit.xml.dist,tests/} ../phpbb/phpBB/ext/"${EXTNAME}"/
 fi
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 5b62c45..0488c3d 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -11,26 +11,26 @@ env:
   IMAGE_ICC: 1
   EPV: 1
   EXECUTABLE_FILES: 1
-  PHPBB_BRANCH: 3.3.x
+  PHPBB_BRANCH: master # TODO: Use stable branch
 
 jobs:
   basic-tests:
     if: ${{ !contains(github.event.head_commit.message, 'skip ci') }}
     name: php ${{ matrix.php-version }}, none none
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-latest
     env:
       PHP_VERSION: ${{ matrix.php-version }}
     strategy:
       fail-fast: false
       matrix:
-        php-version: ['8.1']
+        php-version: ['8.2']
     steps:
       - name: Checkout phpBB
         uses: actions/checkout@v6
         with:
           repository: phpbb/phpbb
           ref: ${{ env.PHPBB_BRANCH }}
-          path: phpBB3
+          path: phpbb
 
       - name: Checkout extension
         uses: actions/checkout@v6
@@ -47,7 +47,7 @@ jobs:
 
       - name: Setup Composer
         id: setup-composer
-        working-directory: phpBB3/phpBB
+        working-directory: phpbb/phpBB
         run: echo "cache-dir=$(composer config cache-files-dir)" >> $GITHUB_OUTPUT
 
       - name: Setup cache
@@ -59,7 +59,7 @@ jobs:
             ${{ runner.os }}-composer-
 
       - name: Setup environment for phpBB
-        working-directory: phpBB3
+        working-directory: phpbb
         run: .github/setup-phpbb.sh $DB $PHP_VERSION $NOTESTS
 
       - name: Setup Node
@@ -81,33 +81,33 @@ jobs:
 
       - name: Setup EPV
         if: ${{ env.EPV == 1 }}
-        working-directory: phpBB3/phpBB
-        run: composer require -n --prefer-dist --no-progress phpbb/epv:dev-master
+        working-directory: phpbb/phpBB
+        run: composer require -n --prefer-dist --no-progress phpbb/epv:dev-epv-phpbb4 # TODO: Use stable branch
 
       - name: Run code sniffer
         if: ${{ env.SNIFF == 1 }}
-        working-directory: phpBB3
+        working-directory: phpbb
         run: .github/ext-sniff.sh $EXTNAME $NOTESTS
 
       - name: Check image ICC profiles
         if: ${{ env.IMAGE_ICC == 1 }}
-        working-directory: phpBB3
+        working-directory: phpbb
         run: .github/check-image-icc-profiles.sh
 
       - name: Check executable files
         if: ${{ env.EXECUTABLE_FILES == 1 }}
-        working-directory: phpBB3
+        working-directory: phpbb
         run: .github/ext-check-executable-files.sh ./ $EXTNAME
 
       - name: Run EPV
         if: ${{ env.EPV == 1 }}
-        working-directory: phpBB3
+        working-directory: phpbb
         run: phpBB/vendor/bin/EPV.php run --dir="phpBB/ext/$EXTNAME"
 
   mysql-tests:
     if: ${{ !contains(github.event.head_commit.message, 'skip ci') }}
     name: php ${{ matrix.php-version }}, ${{ matrix.db-type }} ${{ matrix.db-version }}
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-latest
     services:
       mysql:
         image: ${{ (matrix.db-type == 'mysql' || matrix.db-type == 'mariadb') && matrix.db-type || 'mariadb' }}:${{ (matrix.db-type == 'mysql' || matrix.db-type == 'mariadb' && matrix.db-version != 'none') && matrix.db-version || 'latest' }}
@@ -129,12 +129,9 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - php-version: '8.1'
+          - php-version: '8.2'
             db-type: 'mysql'
             db-version: '5.7'
-          - php-version: '8.1'
-            db-type: 'mariadb'
-            db-version: '10.6'
           - php-version: '8.2'
             db-type: 'mariadb'
             db-version: '10.6'
@@ -153,7 +150,7 @@ jobs:
         with:
           repository: phpbb/phpbb
           ref: ${{ env.PHPBB_BRANCH }}
-          path: phpBB3
+          path: phpbb
 
       - name: Checkout extension
         uses: actions/checkout@v6
@@ -170,7 +167,7 @@ jobs:
 
       - name: Setup Composer
         id: setup-composer
-        working-directory: phpBB3/phpBB
+        working-directory: phpbb/phpBB
         run: echo "cache-dir=$(composer config cache-files-dir)" >> $GITHUB_OUTPUT
 
       - name: Setup cache
@@ -182,7 +179,7 @@ jobs:
             ${{ runner.os }}-composer-
 
       - name: Setup environment for phpBB
-        working-directory: phpBB3
+        working-directory: phpbb
         run: .github/setup-phpbb.sh $DB $PHP_VERSION $NOTESTS
 
       - name: Setup Node
@@ -203,23 +200,23 @@ jobs:
           .github/setup-extension.sh $EXTNAME $NOTESTS
 
       - name: Setup database
-        working-directory: phpBB3
+        working-directory: phpbb
         run: .github/setup-database.sh $DB $MYISAM
 
       - name: Setup PHPUnit files
-        working-directory: phpBB3
+        working-directory: phpbb
         run: |
           mkdir -p phpBB/ext/$EXTNAME/ci
           cp -a .github/phpunit* phpBB/ext/$EXTNAME/ci/
 
       - name: Run unit tests
-        working-directory: phpBB3
+        working-directory: phpbb
         run: phpBB/vendor/bin/phpunit --configuration phpBB/ext/$EXTNAME/ci/phpunit-$DB-github.xml --bootstrap tests/bootstrap.php
 
   postgresql-tests:
     if: ${{ !contains(github.event.head_commit.message, 'skip ci') }}
     name: php ${{ matrix.php-version }}, ${{ matrix.db-type }} ${{ matrix.db-version }}
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-latest
     services:
       postgres:
         image: ${{ (matrix.db-type == 'postgres') && matrix.db-type || 'postgres' }}:${{ (matrix.db-type == 'postgres' && matrix.db-version != 'none') && matrix.db-version || 'alpine' }}
@@ -242,7 +239,7 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - php-version: '8.1'
+          - php-version: '8.2'
             db-type: 'postgres'
             db-version: '17-alpine'
           - php-version: '8.4'
@@ -257,7 +254,7 @@ jobs:
         with:
           repository: phpbb/phpbb
           ref: ${{ env.PHPBB_BRANCH }}
-          path: phpBB3
+          path: phpbb
 
       - name: Checkout extension
         uses: actions/checkout@v6
@@ -274,7 +271,7 @@ jobs:
 
       - name: Setup Composer
         id: setup-composer
-        working-directory: phpBB3/phpBB
+        working-directory: phpbb/phpBB
         run: echo "cache-dir=$(composer config cache-files-dir)" >> $GITHUB_OUTPUT
 
       - name: Setup cache
@@ -286,7 +283,7 @@ jobs:
             ${{ runner.os }}-composer-
 
       - name: Setup environment for phpBB
-        working-directory: phpBB3
+        working-directory: phpbb
         run: .github/setup-phpbb.sh $DB $PHP_VERSION $NOTESTS
 
       - name: Setup Node
@@ -307,17 +304,17 @@ jobs:
           .github/setup-extension.sh $EXTNAME $NOTESTS
 
       - name: Setup database
-        working-directory: phpBB3
+        working-directory: phpbb
         run: .github/setup-database.sh $DB $MYISAM
 
       - name: Setup PHPUnit files
-        working-directory: phpBB3
+        working-directory: phpbb
         run: |
           mkdir -p phpBB/ext/$EXTNAME/ci
           cp -a .github/phpunit* phpBB/ext/$EXTNAME/ci/
 
       - name: Run unit tests
-        working-directory: phpBB3
+        working-directory: phpbb
         run: phpBB/vendor/bin/phpunit --configuration phpBB/ext/$EXTNAME/ci/phpunit-$DB-github.xml --bootstrap tests/bootstrap.php
 
   lint:
diff --git a/README.md b/README.md
index ebbf493..bc6b879 100644
--- a/README.md
+++ b/README.md
@@ -27,8 +27,8 @@ It uses the plugins [Litedown](https://s9etextformatter.readthedocs.io/Plugins/L
 
 ### Requirements
 
-- PHP 8.1 or greater
-- phpBB 3.3 or greater
+- PHP 8.2 or greater
+- phpBB 4.0 or greater
 
 ### Support
 
diff --git a/composer.json b/composer.json
index 160f156..b93d5bb 100644
--- a/composer.json
+++ b/composer.json
@@ -3,8 +3,8 @@
 	"type": "phpbb-extension",
 	"description": "Markdown extension for phpBB",
 	"homepage": "https://github.com/AlfredoRamos/phpbb-ext-markdown",
-	"version": "1.5.0",
-	"time": "2025-09-12",
+	"version": "2.0.0-dev",
+	"time": "2025-09-30",
 	"keywords": [
 		"phpbb",
 		"extension",
@@ -23,7 +23,7 @@
 		}
 	],
 	"require": {
-		"php": "^8.1.0",
+		"php": "^8.2.0",
 		"composer/installers": "^2.2.0"
 	},
 	"require-dev": {
@@ -36,7 +36,7 @@
 	"extra": {
 		"display-name": "Markdown",
 		"soft-require": {
-			"phpbb/phpbb": "~3.3.2"
+			"phpbb/phpbb": "~4.0.0"
 		},
 		"version-check": {
 			"host": "alfredoramos.mx",
diff --git a/ext.php b/ext.php
index a3e360a..659cac1 100644
--- a/ext.php
+++ b/ext.php
@@ -14,12 +14,10 @@
 class ext extends base
 {
 	/**
-	 * Check whether or not the extension can be enabled.
-	 *
-	 * @return bool
-	 */
+	* {@inheritdoc}
+	*/
 	public function is_enableable()
 	{
-		return phpbb_version_compare(PHPBB_VERSION, '3.3.2', '>=');
+		return phpbb_version_compare(PHPBB_VERSION, '4.0.0-a1-dev', '>='); // TODO: Use stable version
 	}
 }
diff --git a/tests/functional/markdown_test.php b/tests/functional/markdown_test.php
index 0aee97d..d0e02e2 100644
--- a/tests/functional/markdown_test.php
+++ b/tests/functional/markdown_test.php
@@ -275,8 +275,8 @@ public function test_inline_spoiler()
 		));
 
 		$expected = <<<EOT
-<p>This is a Reddit-style <span class="spoiler markdown" onclick="removeAttribute('style')" style="background:#444;color:transparent">spoiler</span>.<br>
-This is a Discord-style <span class="spoiler markdown" onclick="removeAttribute('style')" style="background:#444;color:transparent">spoiler</span>.</p>
+<p>This is a Reddit-style <span class="spoiler markdown" onclick="this.removeAttribute('style')" style="background:#444;color:transparent">spoiler</span>.<br>
+This is a Discord-style <span class="spoiler markdown" onclick="this.removeAttribute('style')" style="background:#444;color:transparent">spoiler</span>.</p>
 EOT;
 
 		$result = $crawler->filter(sprintf(