diff --git a/.phpcs.xml b/.phpcs.xml
index b51e29af..d6c3b566 100644
--- a/.phpcs.xml
+++ b/.phpcs.xml
@@ -3,7 +3,6 @@
 	<rule ref="./vendor/mediawiki/mediawiki-codesniffer/MediaWiki">
 		<exclude name="MediaWiki.Commenting.FunctionComment.MissingDocumentationProtected" />
 		<exclude name="MediaWiki.Commenting.FunctionComment.MissingDocumentationPublic" />
-		<exclude name="MediaWiki.Commenting.LicenseComment.InvalidLicenseTag" />
 		<exclude name="MediaWiki.WhiteSpace.SpaceBeforeSingleLineComment.NewLineComment" />
 	</rule>
 	<file>.</file>
diff --git a/CategoryTree.alias.php b/CategoryTree.alias.php
index e99b8264..1e0215da 100644
--- a/CategoryTree.alias.php
+++ b/CategoryTree.alias.php
@@ -6,7 +6,7 @@
  * @ingroup Extensions
  * @author Daniel Kinzler, brightbyte.de
  * @copyright © 2006-2008 Daniel Kinzler and others
- * @license GNU General Public Licence 2.0 or later
+ * @license GPL-2.0-or-later
  */
 
 $specialPageAliases = [];
diff --git a/CategoryTree.i18n.magic.php b/CategoryTree.i18n.magic.php
index 5b365b7b..5fec9fcd 100644
--- a/CategoryTree.i18n.magic.php
+++ b/CategoryTree.i18n.magic.php
@@ -6,7 +6,7 @@
  * @ingroup Extensions
  * @author Daniel Kinzler, brightbyte.de
  * @copyright © 2006-2008 Daniel Kinzler
- * @license GNU General Public Licence 2.0 or later
+ * @license GPL-2.0-or-later
  */
 
 $magicWords = [];
diff --git a/CategoryTree.php b/CategoryTree.php
index e0e6934b..697ee270 100644
--- a/CategoryTree.php
+++ b/CategoryTree.php
@@ -8,7 +8,7 @@
  * @ingroup Extensions
  * @author Daniel Kinzler, brightbyte.de
  * @copyright © 2006-2008 Daniel Kinzler and others
- * @license GNU General Public Licence 2.0 or later
+ * @license GPL-2.0-or-later
  */
 
 if ( function_exists( 'wfLoadExtension' ) ) {
diff --git a/composer.json b/composer.json
index 4935f4ff..0107a5d4 100644
--- a/composer.json
+++ b/composer.json
@@ -2,7 +2,7 @@
 	"require-dev": {
 		"jakub-onderka/php-parallel-lint": "1.0.0",
 		"jakub-onderka/php-console-highlighter": "0.3.2",
-		"mediawiki/mediawiki-codesniffer": "17.0.0",
+		"mediawiki/mediawiki-codesniffer": "18.0.0",
 		"mediawiki/minus-x": "0.3.1",
 		"mediawiki/mediawiki-phan-config": "0.2.0"
 	},
diff --git a/includes/CategoryTree.php b/includes/CategoryTree.php
index f7eb5d24..5fdb117e 100644
--- a/includes/CategoryTree.php
+++ b/includes/CategoryTree.php
@@ -7,7 +7,7 @@
  * @ingroup Extensions
  * @author Daniel Kinzler, brightbyte.de
  * @copyright © 2006-2007 Daniel Kinzler
- * @license GNU General Public Licence 2.0 or later
+ * @license GPL-2.0-or-later
  */
 
 class CategoryTree {
diff --git a/includes/CategoryTreeHidePrefix.php b/includes/CategoryTreeHidePrefix.php
index 7d713610..ac25b529 100644
--- a/includes/CategoryTreeHidePrefix.php
+++ b/includes/CategoryTreeHidePrefix.php
@@ -8,7 +8,7 @@
  * @ingroup Extensions
  * @author Daniel Kinzler, brightbyte.de
  * @copyright © 2006 Daniel Kinzler
- * @license GNU General Public Licence 2.0 or later
+ * @license GPL-2.0-or-later
  */
 class CategoryTreeHidePrefix {
 
diff --git a/includes/CategoryTreeHooks.php b/includes/CategoryTreeHooks.php
index 85d555dc..880c7ca8 100644
--- a/includes/CategoryTreeHooks.php
+++ b/includes/CategoryTreeHooks.php
@@ -7,7 +7,7 @@
  * @ingroup Extensions
  * @author Daniel Kinzler, brightbyte.de
  * @copyright © 2006-2008 Daniel Kinzler and others
- * @license GNU General Public Licence 2.0 or later
+ * @license GPL-2.0-or-later
  */
 
 class CategoryTreeHooks {
diff --git a/includes/CategoryTreeMode.php b/includes/CategoryTreeMode.php
index a80e81bd..7a811184 100644
--- a/includes/CategoryTreeMode.php
+++ b/includes/CategoryTreeMode.php
@@ -7,7 +7,7 @@
  * @ingroup Extensions
  * @author Daniel Kinzler, brightbyte.de
  * @copyright © 2006 Daniel Kinzler
- * @license GNU General Public Licence 2.0 or later
+ * @license GPL-2.0-or-later
  */
 class CategoryTreeMode {
 
diff --git a/includes/CategoryTreePage.php b/includes/CategoryTreePage.php
index 587b0c6f..807083ac 100644
--- a/includes/CategoryTreePage.php
+++ b/includes/CategoryTreePage.php
@@ -7,7 +7,7 @@
  * @ingroup Extensions
  * @author Daniel Kinzler, brightbyte.de
  * @copyright © 2006 Daniel Kinzler
- * @license GNU General Public Licence 2.0 or later
+ * @license GPL-2.0-or-later
  */
 
 class CategoryTreePage extends SpecialPage {