diff --git a/class.jetpack.php b/class.jetpack.php
index ce849331852f5..e2c62ee1340a2 100644
--- a/class.jetpack.php
+++ b/class.jetpack.php
@@ -5537,8 +5537,10 @@ public static function check_privacy( $file ) {
 
 	/**
 	 * Helper method for multicall XMLRPC.
+	 *
+	 * @param ...$args Args for the async_call.
 	 */
-	public static function xmlrpc_async_call() {
+	public static function xmlrpc_async_call( ...$args ) {
 		global $blog_id;
 		static $clients = array();
 
@@ -5552,8 +5554,6 @@ public static function xmlrpc_async_call() {
 			add_action( 'shutdown', array( 'Jetpack', 'xmlrpc_async_call' ) );
 		}
 
-		$args = func_get_args();
-
 		if ( ! empty( $args[0] ) ) {
 			call_user_func_array( array( $clients[ $client_blog_id ], 'addCall' ), $args );
 		} elseif ( is_multisite() ) {
diff --git a/class.json-api.php b/class.json-api.php
index be2c9846ab71f..144ef92c365e6 100644
--- a/class.json-api.php
+++ b/class.json-api.php
@@ -79,8 +79,7 @@ static function is_falsy( $value ) {
 		return false;
 	}
 
-	function __construct() {
-		$args = func_get_args();
+	function __construct( ...$args ) {
 		call_user_func_array( array( $this, 'setup_inputs' ), $args );
 	}
 
diff --git a/modules/comments/base.php b/modules/comments/base.php
index fb9d96856250a..137dd982c5ce0 100644
--- a/modules/comments/base.php
+++ b/modules/comments/base.php
@@ -45,13 +45,13 @@ protected function setup_filters() {
 	 * @param ...
 	 * @return false|string false if it's not a Highlander POST request.  The matching credentials slug if it is.
 	 */
-	function is_highlander_comment_post() {
+	function is_highlander_comment_post( ...$args ) {
 		if ( empty( $_POST['hc_post_as'] ) ) {
 			return false;
 		}
 
-		if ( func_num_args() ) {
-			foreach ( func_get_args() as $id_source ) {
+		if ( $args ) {
+			foreach ( $args as $id_source ) {
 				if ( $id_source === $_POST['hc_post_as'] ) {
 					return $id_source;
 				}
diff --git a/packages/jitm/tests/php/test_JITM.php b/packages/jitm/tests/php/test_JITM.php
index ba5ae63d66ff6..4f8f9058acf09 100644
--- a/packages/jitm/tests/php/test_JITM.php
+++ b/packages/jitm/tests/php/test_JITM.php
@@ -97,8 +97,7 @@ protected function mock_filters( $filters ) {
 		$builder->setNamespace( __NAMESPACE__ )
 			->setName( 'apply_filters' )
 			->setFunction(
-				function() {
-					$current_args = func_get_args();
+				function( ...$current_args ) {
 					foreach ( $this->mocked_filters as $filter ) {
 						if ( array_slice( $filter, 0, -1 ) === $current_args ) {
 							return array_pop( $filter );
@@ -140,9 +139,8 @@ protected function mock_do_action() {
 		$builder = new MockBuilder();
 		$builder->setNamespace( __NAMESPACE__ )
 			->setName( 'do_action' )
-			->setFunction( function() {
+			->setFunction( function( ...$args ) {
 				global $actions;
-				$args = func_get_args();
 				$name = array_shift( $args );
 
 				if ( is_null( $actions ) ) {
diff --git a/packages/status/tests/php/test_Status.php b/packages/status/tests/php/test_Status.php
index dd0c9469c129d..b834ceb57f6b6 100644
--- a/packages/status/tests/php/test_Status.php
+++ b/packages/status/tests/php/test_Status.php
@@ -77,7 +77,7 @@ public function test_is_development_mode_filter_bool() {
 		) );
 
 		$this->assertFalse( $this->status->is_development_mode() );
-		
+
 		$filters_mock->disable();
 	}
 
@@ -86,7 +86,7 @@ public function test_is_development_mode_filter_bool() {
 	 */
 	public function test_is_development_mode_localhost() {
 		$this->mock_function( 'site_url', 'localhost' );
-		
+
 		$filters_mock = $this->mock_filters( array(
 			array( 'jetpack_development_mode', false, false ),
 			array( 'jetpack_development_mode', true, true ),
@@ -101,7 +101,7 @@ public function test_is_development_mode_localhost() {
      * @covers Automattic\Jetpack\Status::is_development_mode
      *
      * @runInSeparateProcess
-     */	
+     */
 	public function test_is_development_mode_constant() {
 		$this->mock_function( 'site_url', $this->site_url );
 		$filters_mock = $this->mock_filters( array(
@@ -204,9 +204,7 @@ protected function mock_function_with_args( $function_name, $args = array() ) {
 		$builder->setNamespace( __NAMESPACE__ )
 			->setName( $function_name )
 			->setFunction(
-				function() use ( &$args ) {
-					$current_args = func_get_args();
-
+				function( ...$current_args ) use ( &$args ) {
 					foreach ( $args as $arg ) {
 						if ( array_slice( $arg, 0, -1 ) === $current_args ) {
 							return array_pop( $arg );
diff --git a/packages/sync/src/Listener.php b/packages/sync/src/Listener.php
index dc9711843ca0d..417bc745ac152 100644
--- a/packages/sync/src/Listener.php
+++ b/packages/sync/src/Listener.php
@@ -106,13 +106,11 @@ function can_add_to_queue( $queue ) {
 			   ( ( $queue_size + 1 ) < $this->sync_queue_size_limit );
 	}
 
-	function full_sync_action_handler() {
-		$args = func_get_args();
+	function full_sync_action_handler( ...$args ) {
 		$this->enqueue_action( current_filter(), $args, $this->full_sync_queue );
 	}
 
-	function action_handler() {
-		$args = func_get_args();
+	function action_handler( ...$args ) {
 		$this->enqueue_action( current_filter(), $args, $this->sync_queue );
 	}
 
diff --git a/sal/class.json-api-links.php b/sal/class.json-api-links.php
index 5b18431f9995a..21450a5287bd9 100644
--- a/sal/class.json-api-links.php
+++ b/sal/class.json-api-links.php
@@ -18,7 +18,7 @@ public static function getInstance() {
 	}
 
 	// protect these methods for singleton
-	protected function __construct() { 
+	protected function __construct() {
 		$this->api = WPCOM_JSON_API::init();
 	}
 	private function __clone() { }
@@ -29,11 +29,10 @@ private function __wakeup() { }
 	 *
 	 * Used to construct meta links in API responses
 	 *
-	 * @param mixed $args Optional arguments to be appended to URL
+	 * @param mixed ...$args Optional arguments to be appended to URL
 	 * @return string Endpoint URL
 	 **/
-	function get_link() {
-		$args   = func_get_args();
+	function get_link( ...$args ) {
 		$format = array_shift( $args );
 		$base = WPCOM_JSON_API__BASE;
 
@@ -127,7 +126,7 @@ function get_external_service_link( $external_service, $path = '' ) {
 	 *   maximum available version of /animals/%s, e.g. 1.1
 	 *
 	 * This method is used in get_link() to construct meta links for API responses.
-	 * 
+	 *
 	 * @param $template_path string The generic endpoint path, e.g. /sites/%s
 	 * @param $path string The current endpoint path, relative to the version, e.g. /sites/12345
 	 * @param $request_method string Request method used to access the endpoint path