diff --git a/admin-command.php b/admin-command.php
index 25eac29..b96329b 100644
--- a/admin-command.php
+++ b/admin-command.php
@@ -7,7 +7,7 @@
 /**
  * Open /wp-admin/ in a browser.
  */
-$wp_admin = function() {
+function wp_cli_admin_command() {
 	switch ( strtoupper( substr( PHP_OS, 0, 3 ) ) ) {
 		case 'DAR':
 			$exec = 'open';
@@ -19,5 +19,5 @@
 			$exec = 'xdg-open';
 	}
 	passthru( $exec . ' ' . escapeshellarg( admin_url() ) );
-};
-WP_CLI::add_command( 'admin', $wp_admin );
+}
+WP_CLI::add_command( 'admin', 'wp_cli_admin_command' );
diff --git a/composer.json b/composer.json
index 9c3b2df..bda1de0 100644
--- a/composer.json
+++ b/composer.json
@@ -8,7 +8,7 @@
         "wp-cli/wp-cli": "^2"
     },
     "require-dev": {
-        "wp-cli/wp-cli-tests": "^3.0.11"
+        "wp-cli/wp-cli-tests": "^4"
     },
     "config": {
         "process-timeout": 7200,
@@ -38,6 +38,7 @@
         "behat-rerun": "rerun-behat-tests",
         "lint": "run-linter-tests",
         "phpcs": "run-phpcs-tests",
+        "phpcbf": "run-phpcbf-cleanup",
         "phpunit": "run-php-unit-tests",
         "prepare-tests": "install-package-tests",
         "test": [
diff --git a/phpcs.xml.dist b/phpcs.xml.dist
new file mode 100644
index 0000000..ea0a892
--- /dev/null
+++ b/phpcs.xml.dist
@@ -0,0 +1,55 @@
+<?xml version="1.0"?>
+<ruleset name="WP-CLI-cache">
+	<description>Custom ruleset for WP-CLI admin-command</description>
+
+	<!--
+	#############################################################################
+	COMMAND LINE ARGUMENTS
+	For help understanding this file: https://github.com/squizlabs/PHP_CodeSniffer/wiki/Annotated-ruleset.xml
+	For help using PHPCS: https://github.com/squizlabs/PHP_CodeSniffer/wiki/Usage
+	#############################################################################
+	-->
+
+	<!-- What to scan. -->
+	<file>.</file>
+
+	<!-- Show progress. -->
+	<arg value="p"/>
+
+	<!-- Strip the filepaths down to the relevant bit. -->
+	<arg name="basepath" value="./"/>
+
+	<!-- Check up to 8 files simultaneously. -->
+	<arg name="parallel" value="8"/>
+
+	<!--
+	#############################################################################
+	USE THE WP_CLI_CS RULESET
+	#############################################################################
+	-->
+
+	<rule ref="WP_CLI_CS"/>
+
+	<!--
+	#############################################################################
+	PROJECT SPECIFIC CONFIGURATION FOR SNIFFS
+	#############################################################################
+	-->
+
+	<!-- For help understanding the `testVersion` configuration setting:
+		 https://github.com/PHPCompatibility/PHPCompatibility#sniffing-your-code-for-compatibility-with-specific-php-versions -->
+	<config name="testVersion" value="5.6-"/>
+
+	<!-- Make this sniff slightly less finicky. The WP Core default is 40. -->
+	<rule ref="Generic.Formatting.MultipleStatementAlignment">
+		<properties>
+			<property name="maxPadding" value="20"/>
+		</properties>
+	</rule>
+
+	<!-- Exclude existing classes from the prefix rule as it would break BC to prefix them now. -->
+	<rule ref="WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedClassFound">
+		<exclude-pattern>*/src/Admin_Command\.php$</exclude-pattern>
+	</rule>
+
+</ruleset>