diff --git a/UniversalLanguageSelector.php b/UniversalLanguageSelector.php
index 97e322cb..5a99f50e 100644
--- a/UniversalLanguageSelector.php
+++ b/UniversalLanguageSelector.php
@@ -23,7 +23,8 @@ if ( function_exists( 'wfLoadExtension' ) ) {
 	// Keep i18n globals so mergeMessageFileList.php doesn't break
 	$wgMessagesDirs['UniversalLanguageSelector'] = __DIR__ . '/i18n';
 	/* wfWarn(
-		'Deprecated PHP entry point used for UniversalLanguageSelector extension. Please use wfLoadExtension instead, ' .
+		'Deprecated PHP entry point used for UniversalLanguageSelector extension. ' .
+		'Please use wfLoadExtension instead, ' .
 		'see https://www.mediawiki.org/wiki/Extension_registration for more details.'
 	); */
 	return;
diff --git a/composer.json b/composer.json
index 005a07fb..df11b180 100644
--- a/composer.json
+++ b/composer.json
@@ -22,11 +22,13 @@
 		"mediawiki/cldr": "Language names in all languages"
 	},
 	"require-dev": {
-		"jakub-onderka/php-parallel-lint": "0.9.*"
+		"jakub-onderka/php-parallel-lint": "0.9.*",
+		"mediawiki/mediawiki-codesniffer": "0.3.0"
 	},
 	"scripts": {
 		"test": [
-			"parallel-lint . --exclude vendor"
+			"parallel-lint . --exclude vendor",
+			"phpcs -p -s"
 		]
 	}
 }
diff --git a/phpcs.xml b/phpcs.xml
new file mode 100644
index 00000000..cb19440e
--- /dev/null
+++ b/phpcs.xml
@@ -0,0 +1,7 @@
+<?xml version="1.0"?>
+<ruleset>
+	<rule ref="vendor/mediawiki/mediawiki-codesniffer/MediaWiki"/>
+	<file>.</file>
+	<arg name="extensions" value="php"/>
+	<exclude-pattern>vendor</exclude-pattern>
+</ruleset>