diff --git a/composer.json b/composer.json
index 5b2b9b64..e5fc6379 100644
--- a/composer.json
+++ b/composer.json
@@ -26,7 +26,7 @@
 	},
 	"require-dev": {
 		"jakub-onderka/php-parallel-lint": "1.0.0",
-		"mediawiki/mediawiki-codesniffer": "18.0.0",
+		"mediawiki/mediawiki-codesniffer": "20.0.0",
 		"jakub-onderka/php-console-highlighter": "0.3.2",
 		"mediawiki/minus-x": "0.3.1"
 	},
diff --git a/data/LanguageNameSearch.php b/data/LanguageNameSearch.php
index 2b3b78c1..1fcebef2 100644
--- a/data/LanguageNameSearch.php
+++ b/data/LanguageNameSearch.php
@@ -34,7 +34,7 @@ class LanguageNameSearch {
 	 *
 	 * @param string $searchKey
 	 * @param int $typos
-	 * @param string $userLanguage Language tag.
+	 * @param string|null $userLanguage Language tag.
 	 * @return array
 	 */
 	public static function search( $searchKey, $typos = 0, $userLanguage = null ) {
diff --git a/includes/ResourceLoaderULSJsonMessageModule.php b/includes/ResourceLoaderULSJsonMessageModule.php
index c9e78a6b..465a5785 100644
--- a/includes/ResourceLoaderULSJsonMessageModule.php
+++ b/includes/ResourceLoaderULSJsonMessageModule.php
@@ -14,7 +14,7 @@ class ResourceLoaderULSJsonMessageModule extends ResourceLoaderModule {
 	/**
 	 * Part of the ResourceLoader module interface.
 	 * Declares the core ext.uls.i18n module as a dependency.
-	 * @param ResourceLoaderContext $context
+	 * @param ResourceLoaderContext|null $context
 	 * @return string[] Module names.
 	 */
 	public function getDependencies( ResourceLoaderContext $context = null ) {