diff --git a/src/Formatter/Hook_Formatter.php b/src/Formatter/Hook_Formatter.php
index 15876a4..34f2fb6 100644
--- a/src/Formatter/Hook_Formatter.php
+++ b/src/Formatter/Hook_Formatter.php
@@ -3,38 +3,56 @@ declare( strict_types=1 );
 
 namespace Rarst\Laps\Formatter;
 
+use WP_Hook;
+
 /**
- * Formatter for WordPress hook callbacks.
+ * Formatter to process callbacks from a hook instance.
  */
 class Hook_Formatter {
 
-	/** @var array $truncate_paths List of base paths to strip for readability. */
-	protected $truncate_paths;
+	/** @var array $truncate_paths Paths to truncate from includes. */
+	protected $truncate_paths = [];
 
 	/**
-	 * Set up truncate paths.
+	 * Set up object properties.
 	 */
 	public function __construct() {
 
-		$this->truncate_paths = array_filter( [
-			wp_normalize_path( ABSPATH ),
+		// TODO inject paths instead of reaching for global constants.
+		$this->truncate_paths = [
 			wp_normalize_path( WP_CONTENT_DIR ),
-		] );
+			wp_normalize_path( ABSPATH ),
+			'wp-admin/',
+		];
 	}
 
 	/**
-	 * Convert hook callbacks array to a list of readable names.
+	 * @psalm-type  Callback = string|object|array
+	 * @psalm-type  AcceptedArgs = int
+	 * @psalm-type  Hook = array{function: Callback, accepted_args: AcceptedArgs}
+	 * @psalm-type  Priority = array-key
+	 * @psalm-type  Hooks = array<Priority, array<Hook>>
 	 *
-	 * @param array $hook Array of callbacks, registered for the hook.
+	 * @param WP_Hook|array $hook Hook instance or callbacks array.
+	 * @psalm-param WP_Hook|Hooks $hook
 	 *
 	 * @return array
 	 */
-	public function format( array $hook ): array {
+	public function format( $hook ): array {
+
+		$callbacks = [];
+
+		if ( $hook instanceof WP_Hook ) {
+			/** @psalm-var Hooks $hook->callbacks */
+			$hook = $hook->callbacks;
+		}
 
 		if ( empty( $hook ) ) {
-			return [];
+			return $callbacks;
 		}
 
+		ksort( $hook );
+
 		/**
 		 * Empty priorities produce empty arrays in PHP 7.2 and unpack operator doesn't accept empty array in 7.3.
 		 *
@@ -44,36 +62,48 @@ class Hook_Formatter {
 		$hook = array_filter( $hook );
 
 		if ( empty( $hook ) ) {
-			return [];
+			return $callbacks;
 		}
 
-		/** @var array $functions */
+		/** @psalm-suppress InvalidArgument */
 		$functions = array_merge( ...$hook );
 
-		return array_map( [ $this, 'format_callback' ], $functions );
+		/** @psalm-var Hook[] $functions */
+		foreach ( $functions as $function ) {
+			/** @psalm-var Hook $function */
+			$callback = $this->get_callback_name( $function['function'], $function['accepted_args'] );
+
+			if ( false !== strpos( $callback, 'Hook_Collector' ) ) {
+				continue;
+			}
+
+			$callbacks[] = $callback;
+		}
+
+		return $callbacks;
 	}
 
 	/**
-	 * Convert callback data array to a readable name.
-	 *
-	 * @param array $callback_data Callback data, registered for the hook.
-	 *
-	 * @return string
+	 * @param string|object|array $callback Hook callback.
+	 * @param int                 $args     Number of accepted arguments.
 	 */
-	protected function format_callback( array $callback_data ): string {
+	protected function get_callback_name( $callback, int $args ): string {
 
-		$callback = $callback_data['function'];
-		$args     = $callback_data['accepted_args'];
+		switch ( gettype( $callback ) ) {
+			case 'object':
+				$name = $this->get_class_name( $callback );
+				break;
 
-		if ( is_string( $callback ) ) {
-			$name = $callback;
-		} elseif ( is_array( $callback ) ) {
-			$class = is_object( $callback[0] ) ? $this->get_class_name( $callback[0] ) : $callback[0];
-			$name  = $class . '::' . $callback[1];
-		} elseif ( is_object( $callback ) ) {
-			$name = $this->get_class_name( $callback );
-		} else {
-			$name = 'unknown';
+			case 'array':
+				/** @psalm-var array{0: object|string, 1: string} $callback */
+				$class = is_string( $callback[0] )
+					? $callback[0] . '::'
+					: $this->get_class_name( $callback[0] ) . '->';
+				$name  = $class . $callback[1];
+				break;
+
+			default:
+				$name = $callback;
 		}
 
 		return $name . ( ( 1 === $args ) ? '' : "({$args})" );
@@ -118,14 +148,11 @@ class Hook_Formatter {
 	 * @return string
 	 */
 	protected function shorten_path( string $path ): string {
-
 		$path = wp_normalize_path( $path );
 		$path = str_replace( $this->truncate_paths, '', $path );
-
-		if ( 0 === strpos( $path, './' ) ) {
+		if ( isset( $path[1] ) && ':' === $path[1] ) {
 			$path = substr( $path, 2 );
 		}
-
 		$path = ltrim( $path, '/' );
 
 		return $path;
diff --git a/tests/Formatter/HookTest.php b/tests/Formatter/HookTest.php
index 7843ff0..ab9216e 100644
--- a/tests/Formatter/HookTest.php
+++ b/tests/Formatter/HookTest.php
@@ -58,5 +58,26 @@ class HookTest extends LapsTestCase {
 
 		$this->assertEquals( [], $formatter->format( [] ) );
 	}
-}
 
+	/**
+	 * @depends test__construct
+	 */
+	public function testFormatWpHook( Hook_Formatter $formatter ) {
+
+		if ( ! class_exists( 'WP_Hook' ) ) {
+			eval( 'class WP_Hook { public $callbacks = []; }' );
+		}
+
+		$wp_hook            = new \WP_Hook();
+		$wp_hook->callbacks = [
+			10 => [
+				[ 'function' => 'trim', 'accepted_args' => 1 ],
+			],
+		];
+
+		$result = $formatter->format( $wp_hook );
+
+		$this->assertIsArray( $result );
+		$this->assertEquals( [ 'trim' ], $result );
+	}
+}