diff --git a/activitypub.php b/activitypub.php
index dbca209..e0f7880 100644
--- a/activitypub.php
+++ b/activitypub.php
@@ -21,50 +21,50 @@ namespace Activitypub;
 function init() {
 	\defined( 'ACTIVITYPUB_HASHTAGS_REGEXP' ) || \define( 'ACTIVITYPUB_HASHTAGS_REGEXP', '(?:(?<=\s)|^)#(\w*[A-Za-z_]+\w*)' );
 
-	require_once dirname( __FILE__ ) . '/includes/table/followers-list.php';
-	require_once dirname( __FILE__ ) . '/includes/class-signature.php';
-	require_once dirname( __FILE__ ) . '/includes/peer/class-followers.php';
-	require_once dirname( __FILE__ ) . '/includes/functions.php';
+	require_once \dirname( __FILE__ ) . '/includes/table/followers-list.php';
+	require_once \dirname( __FILE__ ) . '/includes/class-signature.php';
+	require_once \dirname( __FILE__ ) . '/includes/peer/class-followers.php';
+	require_once \dirname( __FILE__ ) . '/includes/functions.php';
 
-	require_once dirname( __FILE__ ) . '/includes/class-activity-dispatcher.php';
+	require_once \dirname( __FILE__ ) . '/includes/class-activity-dispatcher.php';
 	\Activitypub\Activity_Dispatcher::init();
 
-	require_once dirname( __FILE__ ) . '/includes/model/class-activity.php';
-	require_once dirname( __FILE__ ) . '/includes/model/class-post.php';
+	require_once \dirname( __FILE__ ) . '/includes/model/class-activity.php';
+	require_once \dirname( __FILE__ ) . '/includes/model/class-post.php';
 	\Activitypub\Model\Post::init();
 
-	require_once dirname( __FILE__ ) . '/includes/class-activitypub.php';
+	require_once \dirname( __FILE__ ) . '/includes/class-activitypub.php';
 	\Activitypub\Activitypub::init();
 
 	// Configure the REST API route
-	require_once dirname( __FILE__ ) . '/includes/rest/class-outbox.php';
+	require_once \dirname( __FILE__ ) . '/includes/rest/class-outbox.php';
 	\Activitypub\Rest\Outbox::init();
 
-	require_once dirname( __FILE__ ) . '/includes/rest/class-inbox.php';
+	require_once \dirname( __FILE__ ) . '/includes/rest/class-inbox.php';
 	\Activitypub\Rest\Inbox::init();
 
-	require_once dirname( __FILE__ ) . '/includes/rest/class-followers.php';
+	require_once \dirname( __FILE__ ) . '/includes/rest/class-followers.php';
 	\Activitypub\Rest\Followers::init();
 
-	require_once dirname( __FILE__ ) . '/includes/rest/class-following.php';
+	require_once \dirname( __FILE__ ) . '/includes/rest/class-following.php';
 	\Activitypub\Rest\Following::init();
 
-	require_once dirname( __FILE__ ) . '/includes/rest/class-webfinger.php';
+	require_once \dirname( __FILE__ ) . '/includes/rest/class-webfinger.php';
 	\Activitypub\Rest\Webfinger::init();
 
-	require_once dirname( __FILE__ ) . '/includes/rest/class-nodeinfo.php';
+	require_once \dirname( __FILE__ ) . '/includes/rest/class-nodeinfo.php';
 	\Activitypub\Rest\NodeInfo::init();
 
-	require_once dirname( __FILE__ ) . '/includes/class-admin.php';
+	require_once \dirname( __FILE__ ) . '/includes/class-admin.php';
 	\Activitypub\Admin::init();
 
-	require_once dirname( __FILE__ ) . '/includes/class-hashtag.php';
+	require_once \dirname( __FILE__ ) . '/includes/class-hashtag.php';
 	\Activitypub\Hashtag::init();
 
-	require_once dirname( __FILE__ ) . '/includes/class-debug.php';
+	require_once \dirname( __FILE__ ) . '/includes/class-debug.php';
 	\Activitypub\Debug::init();
 
-	require_once dirname( __FILE__ ) . '/includes/class-health-check.php';
+	require_once \dirname( __FILE__ ) . '/includes/class-health-check.php';
 	\Activitypub\Health_Check::init();
 }
 add_action( 'plugins_loaded', '\Activitypub\init' );
diff --git a/includes/class-activitypub.php b/includes/class-activitypub.php
index 07d9223..49e022a 100644
--- a/includes/class-activitypub.php
+++ b/includes/class-activitypub.php
@@ -57,14 +57,14 @@ class Activitypub {
 		$accept_header = $_SERVER['HTTP_ACCEPT'];
 
 		if (
-			stristr( $accept_header, 'application/activity+json' ) ||
-			stristr( $accept_header, 'application/ld+json' )
+			\stristr( $accept_header, 'application/activity+json' ) ||
+			\stristr( $accept_header, 'application/ld+json' )
 		) {
 			return $json_template;
 		}
 
 		// accept header as an array
-		$accept = \explode( ',', trim( $accept_header ) );
+		$accept = \explode( ',', \trim( $accept_header ) );
 
 		if (
 			\in_array( 'application/ld+json; profile="https://www.w3.org/ns/activitystreams"', $accept, true ) ||
@@ -113,11 +113,11 @@ class Activitypub {
 		}
 
 		if ( 'publish' === $new_status && 'publish' !== $old_status ) {
-			\wp_schedule_single_event( time(), 'activitypub_send_post_activity', array( $post->ID ) );
+			\wp_schedule_single_event( \time(), 'activitypub_send_post_activity', array( $post->ID ) );
 		} elseif ( 'publish' === $new_status ) {
-			\wp_schedule_single_event( time(), 'activitypub_send_update_activity', array( $post->ID ) );
+			\wp_schedule_single_event( \time(), 'activitypub_send_update_activity', array( $post->ID ) );
 		} elseif ( 'trash' === $new_status ) {
-			\wp_schedule_single_event( time(), 'activitypub_send_delete_activity', array( get_permalink( $post ) ) );
+			\wp_schedule_single_event( \time(), 'activitypub_send_delete_activity', array( get_permalink( $post ) ) );
 		}
 	}
 
diff --git a/includes/class-admin.php b/includes/class-admin.php
index 51513cb..fbdf85d 100644
--- a/includes/class-admin.php
+++ b/includes/class-admin.php
@@ -39,14 +39,14 @@ class Admin {
 	 * Load settings page
 	 */
 	public static function settings_page() {
-		\load_template( dirname( __FILE__ ) . '/../templates/settings.php' );
+		\load_template( \dirname( __FILE__ ) . '/../templates/settings.php' );
 	}
 
 	/**
 	 * Load user settings page
 	 */
 	public static function followers_list_page() {
-		\load_template( dirname( __FILE__ ) . '/../templates/followers-list.php' );
+		\load_template( \dirname( __FILE__ ) . '/../templates/followers-list.php' );
 	}
 
 	/**
diff --git a/includes/class-debug.php b/includes/class-debug.php
index 5539cf6..ac8b8bf 100644
--- a/includes/class-debug.php
+++ b/includes/class-debug.php
@@ -21,7 +21,7 @@ class Debug {
 	}
 
 	public static function write_log( $log ) {
-		if ( is_array( $log ) || is_object( $log ) ) {
+		if ( \is_array( $log ) || \is_object( $log ) ) {
 			\error_log( \print_r( $log, true ) );
 		} else {
 			\error_log( $log );
diff --git a/includes/functions.php b/includes/functions.php
index 4eeeb33..a2587ee 100644
--- a/includes/functions.php
+++ b/includes/functions.php
@@ -194,7 +194,7 @@ function get_identifier_settings( $user_id ) {
 			<td>
 				<p><code><?php echo \esc_html( \Activitypub\get_webfinger_resource( $user_id ) ); ?></code> or <code><?php echo \esc_url( \get_author_posts_url( $user_id ) ); ?></code></p>
 				<?php // translators: the webfinger resource ?>
-				<p class="description"><?php printf( \esc_html__( 'Try to follow "@%s" in the Mastodon/Friendica search field.', 'activitypub' ), \esc_html( \Activitypub\get_webfinger_resource( $user_id ) ) ); ?></p>
+				<p class="description"><?php \printf( \esc_html__( 'Try to follow "@%s" in the Mastodon/Friendica search field.', 'activitypub' ), \esc_html( \Activitypub\get_webfinger_resource( $user_id ) ) ); ?></p>
 			</td>
 		</tr>
 	</tbody>
@@ -236,7 +236,7 @@ function url_to_authorid( $url ) {
 	}
 
 	// first, check to see if there is a 'author=N' to match against
-	if ( preg_match( '/[?&]author=(\d+)/i', $url, $values ) ) {
+	if ( \preg_match( '/[?&]author=(\d+)/i', $url, $values ) ) {
 		$id = absint( $values[1] );
 		if ( $id ) {
 			return $id;
@@ -253,10 +253,10 @@ function url_to_authorid( $url ) {
 
 	// generate rewrite rule for the author url
 	$author_rewrite = $wp_rewrite->get_author_permastruct();
-	$author_regexp = str_replace( '%author%', '', $author_rewrite );
+	$author_regexp = \str_replace( '%author%', '', $author_rewrite );
 
 	// match the rewrite rule with the passed url
-	if ( preg_match( '/https?:\/\/(.+)' . preg_quote( $author_regexp, '/' ) . '([^\/]+)/i', $url, $match ) ) {
+	if ( \preg_match( '/https?:\/\/(.+)' . \preg_quote( $author_regexp, '/' ) . '([^\/]+)/i', $url, $match ) ) {
 		$user = get_user_by( 'slug', $match[2] );
 		if ( $user ) {
 			return $user->ID;
diff --git a/includes/model/class-activity.php b/includes/model/class-activity.php
index 0cfc1c6..470b192 100644
--- a/includes/model/class-activity.php
+++ b/includes/model/class-activity.php
@@ -30,7 +30,7 @@ class Activity {
 		}
 
 		$this->type = \ucfirst( $type );
-		$this->published = \date( 'Y-m-d\TH:i:s\Z', strtotime( 'now' ) );
+		$this->published = \date( 'Y-m-d\TH:i:s\Z', \strtotime( 'now' ) );
 	}
 
 	public function __call( $method, $params ) {
diff --git a/includes/rest/class-inbox.php b/includes/rest/class-inbox.php
index 85d4ba1..e2772ae 100644
--- a/includes/rest/class-inbox.php
+++ b/includes/rest/class-inbox.php
@@ -252,7 +252,7 @@ class Inbox {
 			'comment_author_email' => '',
 			'comment_author_url' => \esc_url_raw( $object['actor'] ),
 			'comment_content' => \esc_url_raw( $object['actor'] ),
-			'comment_type' => \esc_attr( strtolower( $object['type'] ) ),
+			'comment_type' => \esc_attr( \strtolower( $object['type'] ) ),
 			'comment_parent' => 0,
 			'comment_meta' => array(
 				'source_url' => \esc_url_raw( $object['id'] ),
diff --git a/includes/rest/class-outbox.php b/includes/rest/class-outbox.php
index c7ddbcb..a43b74e 100644
--- a/includes/rest/class-outbox.php
+++ b/includes/rest/class-outbox.php
@@ -78,7 +78,7 @@ class Outbox {
 		$json->first = \add_query_arg( 'page', 0, $json->partOf ); // phpcs:ignore
 		$json->last  = \add_query_arg( 'page', ( \ceil ( $json->totalItems / 10 ) ) - 1, $json->partOf ); // phpcs:ignore
 
-		if ( ( ceil ( $json->totalItems / 10 ) ) - 1 > $page ) { // phpcs:ignore
+		if ( ( \ceil ( $json->totalItems / 10 ) ) - 1 > $page ) { // phpcs:ignore
 			$json->next  = \add_query_arg( 'page', ++$page, $json->partOf ); // phpcs:ignore
 		}
 
diff --git a/includes/table/followers-list.php b/includes/table/followers-list.php
index 965cb90..81444ee 100644
--- a/includes/table/followers-list.php
+++ b/includes/table/followers-list.php
@@ -1,7 +1,7 @@
 <?php
 namespace Activitypub\Table;
 
-if ( ! class_exists( '\WP_List_Table' ) ) {
+if ( ! \class_exists( '\WP_List_Table' ) ) {
 		require_once ABSPATH . 'wp-admin/includes/class-wp-list-table.php';
 }
 
diff --git a/templates/settings.php b/templates/settings.php
index cfe3b4a..e4e9532 100644
--- a/templates/settings.php
+++ b/templates/settings.php
@@ -61,7 +61,7 @@
 							<ul>
 							<?php foreach ( $post_types as $post_type ) { ?>
 								<li>
-									<input type="checkbox" id="activitypub_support_post_types" name="activitypub_support_post_types[]" value="<?php echo \esc_attr( $post_type->name ); ?>" <?php echo \checked( true, in_array( $post_type->name, $support_post_types, true ) ); ?> />
+									<input type="checkbox" id="activitypub_support_post_types" name="activitypub_support_post_types[]" value="<?php echo \esc_attr( $post_type->name ); ?>" <?php echo \checked( true, \in_array( $post_type->name, $support_post_types, true ) ); ?> />
 									<label for="<?php echo \esc_attr( $post_type->name ); ?>"><?php echo \esc_html( $post_type->label ); ?></label>
 								</li>
 							<?php } ?>
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index b37004a..e75f0bb 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -1,10 +1,10 @@
 <?php
 
-error_reporting( E_ALL & ~E_NOTICE & ~E_STRICT & ~E_WARNING );
+\error_reporting( E_ALL & ~E_NOTICE & ~E_STRICT & ~E_WARNING );
 
-define( 'WP_DEBUG', false );
+\define( 'WP_DEBUG', false );
 
-$_tests_dir = getenv( 'WP_TESTS_DIR' );
+$_tests_dir = \getenv( 'WP_TESTS_DIR' );
 if ( ! $_tests_dir ) {
 	$_tests_dir = '/tmp/wordpress-tests-lib';
 }
@@ -12,10 +12,10 @@ if ( ! $_tests_dir ) {
 require_once $_tests_dir . '/includes/functions.php';
 
 function _manually_load_plugin() {
-	require dirname( dirname( __FILE__ ) ) . '/activitypub.php';
+	require \dirname( \dirname( __FILE__ ) ) . '/activitypub.php';
 }
 tests_add_filter( 'muplugins_loaded', '_manually_load_plugin' );
 
 require $_tests_dir . '/includes/bootstrap.php';
 
-error_reporting( E_ALL & ~E_NOTICE & ~E_STRICT & ~E_WARNING );
+\error_reporting( E_ALL & ~E_NOTICE & ~E_STRICT & ~E_WARNING );
diff --git a/tests/test-class-db-activitypub-followers.php b/tests/test-class-db-activitypub-followers.php
index 30c6cdb..295bf24 100644
--- a/tests/test-class-db-activitypub-followers.php
+++ b/tests/test-class-db-activitypub-followers.php
@@ -11,13 +11,13 @@ class Test_Db_Activitypub_Followers extends WP_UnitTestCase {
 
 		$db_followers = \Activitypub\Peer\Followers::get_followers( 1 );
 
-		$this->assertEquals( 3, count( $db_followers ) );
+		$this->assertEquals( 3, \count( $db_followers ) );
 
 		$this->assertSame( array( 'https://example.com/author/jon', 'https://example.org/author/doe', 'http://sally.example.org' ), $db_followers );
 	}
 
 	public function test_add_follower() {
-		$follower = 'https://example.com/author/' . time();
+		$follower = 'https://example.com/author/' . \time();
 		\Activitypub\Peer\Followers::add_follower( $follower, 1 );
 
 		$db_followers = \Activitypub\Peer\Followers::get_followers( 1 );