diff --git a/composer.json b/composer.json
index 9885618..256b6aa 100644
--- a/composer.json
+++ b/composer.json
@@ -71,6 +71,7 @@
         "test": [
             "@lint",
             "@phpcs",
+            "@phpstan",
             "@phpunit",
             "@behat"
         ]
diff --git a/phpstan.neon.dist b/phpstan.neon.dist
new file mode 100644
index 0000000..70099aa
--- /dev/null
+++ b/phpstan.neon.dist
@@ -0,0 +1,15 @@
+parameters:
+  level: 6
+  paths:
+    - src
+    - i18n-command.php
+  scanDirectories:
+    - vendor/wp-cli/wp-cli/php
+  scanFiles:
+    - vendor/php-stubs/wordpress-stubs/wordpress-stubs.php
+    - tests/phpstan/scan-files.php
+
+  treatPhpDocTypesAsCertain: false
+
+  stubFiles:
+    - stubs/Gettext.stub
diff --git a/src/AuditCommand.php b/src/AuditCommand.php
index 88e6324..3029561 100644
--- a/src/AuditCommand.php
+++ b/src/AuditCommand.php
@@ -6,8 +6,10 @@
 use Gettext\Translations;
 use Gettext\Utils\ParsedComment;
 use WP_CLI;
+use WP_CLI\Path;
 use WP_CLI\Utils;
 
+
 /**
  * Audit strings in a WordPress project.
  *
@@ -88,8 +90,9 @@ class AuditCommand extends MakePotCommand {
 	 *     # Audit a plugin with GitHub Actions annotations format.
 	 *     $ wp i18n audit wp-content/plugins/hello-world --format=github-actions
 	 *
-	 * @when before_wp_load
-	 *
+	 * @param array<string> $args       Positional arguments.
+	 * @param array<mixed>  $assoc_args Associative arguments.
+	 * @return void
 	 * @throws WP_CLI\ExitException
 	 */
 	public function __invoke( $args, $assoc_args ) {
@@ -98,7 +101,7 @@ public function __invoke( $args, $assoc_args ) {
 			WP_CLI::error( 'Not a valid source directory.' );
 		}
 
-		$this->slug            = Utils\get_flag_value( $assoc_args, 'slug', Utils\basename( $this->source ) );
+		$this->slug            = Utils\get_flag_value( $assoc_args, 'slug', Path::basename( $this->source ) );
 		$this->domain          = Utils\get_flag_value( $assoc_args, 'domain', null );
 		$this->skip_js         = Utils\get_flag_value( $assoc_args, 'skip-js', $this->skip_js );
 		$this->skip_php        = Utils\get_flag_value( $assoc_args, 'skip-php', $this->skip_php );
@@ -108,12 +111,12 @@ public function __invoke( $args, $assoc_args ) {
 		$this->format          = Utils\get_flag_value( $assoc_args, 'format', $this->format );
 		$ignore_domain         = Utils\get_flag_value( $assoc_args, 'ignore-domain', false );
 
-		$include = Utils\get_flag_value( $assoc_args, 'include', [] );
+		$include = Utils\get_flag_value( $assoc_args, 'include', null );
 		if ( ! empty( $include ) ) {
 			$this->include = array_map( 'trim', explode( ',', $include ) );
 		}
 
-		$exclude = Utils\get_flag_value( $assoc_args, 'exclude', [] );
+		$exclude = Utils\get_flag_value( $assoc_args, 'exclude', null );
 		if ( ! empty( $exclude ) ) {
 			$this->exclude = array_map( 'trim', explode( ',', $exclude ) );
 		}
@@ -166,7 +169,7 @@ public function __invoke( $args, $assoc_args ) {
 	 *
 	 * Overrides parent method to suppress log messages when using non-plaintext formats.
 	 *
-	 * @return array
+	 * @return array<string, array<string, mixed>>
 	 */
 	protected function get_main_file_data() {
 		$files = new \IteratorIterator( new \DirectoryIterator( $this->source ) );
@@ -378,7 +381,7 @@ protected function get_comment_text( $comment ) {
 	 * Goes through all extracted strings to find possible mistakes.
 	 *
 	 * @param Translations $translations Translations object.
-	 * @return array Array of issues found.
+	 * @return array<int, array<string, mixed>> Array of issues found.
 	 */
 	protected function collect_audit_issues( $translations ) {
 		$issues = [];
@@ -420,8 +423,6 @@ protected function collect_audit_issues( $translations ) {
 				$comments = array_filter(
 					$comments,
 					function ( $comment ) {
-						/** @var ParsedComment|string $comment */
-						/** @var string $file_header */
 						foreach ( $this->get_file_headers( $this->project_type ) as $file_header ) {
 							if ( 0 === strpos( $this->get_comment_text( $comment ), $file_header ) ) {
 								return false;
@@ -517,7 +518,8 @@ function ( $comment ) {
 	/**
 	 * Outputs audit results in the specified format.
 	 *
-	 * @param array $issues Array of issues found.
+	 * @param array<int, array<string, mixed>> $issues Array of issues found.
+	 * @return void
 	 */
 	protected function output_results( $issues ) {
 		if ( empty( $issues ) ) {
diff --git a/src/BladeCodeExtractor.php b/src/BladeCodeExtractor.php
index 482c68c..3ac184c 100644
--- a/src/BladeCodeExtractor.php
+++ b/src/BladeCodeExtractor.php
@@ -9,6 +9,9 @@
 final class BladeCodeExtractor extends BladeGettextExtractor {
 	use IterableCodeExtractor;
 
+	/**
+	 * @var array<mixed>
+	 */
 	public static $options = [
 		'extractComments' => [ 'translators', 'Translators' ],
 		'constants'       => [],
@@ -42,10 +45,18 @@ final class BladeCodeExtractor extends BladeGettextExtractor {
 		],
 	];
 
+	/**
+	 * @var string
+	 */
 	protected static $functionsScannerClass = 'WP_CLI\I18n\PhpFunctionsScanner';
 
 	/**
 	 * {@inheritdoc}
+	 *
+	 * @param string       $text         The text to extract strings from.
+	 * @param Translations $translations Translations instance.
+	 * @param array<mixed> $options      Extraction options.
+	 * @return void
 	 */
 	public static function fromString( $text, Translations $translations, array $options = [] ) {
 		WP_CLI::debug( "Parsing file {$options['file']}", 'make-pot' );
diff --git a/src/BladeGettextExtractor.php b/src/BladeGettextExtractor.php
index 4fdd055..74c57be 100644
--- a/src/BladeGettextExtractor.php
+++ b/src/BladeGettextExtractor.php
@@ -16,27 +16,26 @@ class BladeGettextExtractor extends \Gettext\Extractors\PhpCode {
 	/**
 	 * Prepares a Blade compiler/engine and returns it.
 	 *
+	 * @param array<string, mixed> $options Options array.
 	 * @return BladeOne
 	 */
-	protected static function getBladeCompiler() {
+	protected static function getBladeCompiler( array $options = [] ) {
+
 		$cache_path     = empty( $options['cachePath'] ) ? sys_get_temp_dir() : $options['cachePath'];
 		$blade_compiler = new BladeOne( null, $cache_path );
 
-		if ( method_exists( $blade_compiler, 'withoutComponentTags' ) ) {
-			$blade_compiler->withoutComponentTags();
-		}
-
 		return $blade_compiler;
 	}
 
 	/**
 	 * Compiles the Blade template string into a PHP string in one step.
 	 *
-	 * @param string $text Blade string to be compiled to a PHP string
+	 * @param string               $text    Blade string to be compiled to a PHP string
+	 * @param array<string, mixed> $options Options array.
 	 * @return string
 	 */
-	protected static function compileBladeToPhp( $text ) {
-		return static::getBladeCompiler()->compileString( $text );
+	protected static function compileBladeToPhp( $text, array $options = [] ) {
+		return static::getBladeCompiler( $options )->compileString( $text );
 	}
 
 	/**
@@ -76,11 +75,17 @@ protected static function extractComponentPropExpressions( $text ) {
 	/**
 	 * {@inheritdoc}
 	 *
+	 * @param string                        $text         The text to extract strings from.
+	 * @param array<\Gettext\Translations> $translations Translations instances.
+	 * @param array<mixed>         $options      Options.
+	 * @return void
+	 *
 	 * Note: In the parent PhpCode class fromString() uses fromStringMultiple() (overridden here)
 	 */
 	public static function fromStringMultiple( $text, array $translations, array $options = [] ) {
-		$php_string  = static::compileBladeToPhp( $text );
+		$php_string = static::compileBladeToPhp( $text, $options );
+
 		$php_string .= static::extractComponentPropExpressions( $text );
-		return parent::fromStringMultiple( $php_string, $translations, $options );
+		parent::fromStringMultiple( $php_string, $translations, $options );
 	}
 }
diff --git a/src/FileDataExtractor.php b/src/FileDataExtractor.php
index f724a6b..2148947 100644
--- a/src/FileDataExtractor.php
+++ b/src/FileDataExtractor.php
@@ -15,10 +15,10 @@ class FileDataExtractor {
 	 *
 	 * @see get_file_data()
 	 *
-	 * @param string $file Path to the file.
-	 * @param array $headers List of headers, in the format array('HeaderKey' => 'Header Name').
+	 * @param string               $file    Path to the file.
+	 * @param array<string, string> $headers List of headers, in the format array('HeaderKey' => 'Header Name').
 	 *
-	 * @return array Array of file headers in `HeaderKey => ['value' => Header Value, 'line' => Line Number]` format.
+	 * @return array<string, array{value: string, line: int}> Array of file headers in `HeaderKey => ['value' => Header Value, 'line' => Line Number]` format.
 	 */
 	public static function get_file_data( $file, $headers ) {
 		// We don't need to write to the file, so just open for reading.
@@ -39,10 +39,10 @@ public static function get_file_data( $file, $headers ) {
 	/**
 	 * Retrieves metadata from a string.
 	 *
-	 * @param string $text String to look for metadata in.
-	 * @param array $headers List of headers.
+	 * @param string               $text    String to look for metadata in.
+	 * @param array<string, string> $headers List of headers.
 	 *
-	 * @return array Array of file headers in `HeaderKey => ['value' => Header Value, 'line' => Line Number]` format.
+	 * @return array<string, array{value: string, line: int}> Array of file headers in `HeaderKey => ['value' => Header Value, 'line' => Line Number]` format.
 	 */
 	public static function get_file_data_from_string( $text, $headers ) {
 		foreach ( $headers as $field => $regex ) {
diff --git a/src/IterableCodeExtractor.php b/src/IterableCodeExtractor.php
index 112264e..e35a898 100644
--- a/src/IterableCodeExtractor.php
+++ b/src/IterableCodeExtractor.php
@@ -9,37 +9,42 @@
 use RecursiveIteratorIterator;
 use SplFileInfo;
 use WP_CLI;
-use WP_CLI\Utils;
+use WP_CLI\Path;
+
+
 
 trait IterableCodeExtractor {
 
+	/**
+	 * @var string
+	 */
 	protected static $dir = '';
 
 	/**
 	 * Extract the translations from a file.
 	 *
-	 * @param array|string $file_or_files A path of a file or files
-	 * @param Translations $translations  The translations instance to append the new translations.
-	 * @param array        $options      {
+	 * @param array<mixed>|string $file_or_files A path of a file or files
+	 * @param Translations         $translations  The translations instance to append the new translations.
+	 * @param array<mixed>         $options      {
 	 *     Optional. An array of options passed down to static::fromString()
 	 *
 	 *     @type bool  $wpExtractTemplates  Extract 'Template Name' headers in theme files. Default 'false'.
 	 *     @type bool  $wpExtractPatterns   Extract 'Title' and 'Description' headers in pattern files. Default 'false'.
-	 *     @type array $restrictFileNames   Skip all files which are not included in this array.
-	 *     @type array $restrictDirectories Skip all directories which are not included in this array.
+	 *     @type array<string> $restrictFileNames   Skip all files which are not included in this array.
+	 *     @type array<string> $restrictDirectories Skip all directories which are not included in this array.
 	 * }
 	 * @return null
 	 */
 	public static function fromFile( $file_or_files, Translations $translations, array $options = [] ) {
 		foreach ( static::getFiles( $file_or_files ) as $file ) {
 			if ( ! empty( $options['restrictFileNames'] ) ) {
-				$basename = Utils\basename( $file );
+				$basename = Path::basename( $file );
 				if ( ! in_array( $basename, $options['restrictFileNames'], true ) ) {
 					continue;
 				}
 			}
 
-			$relative_file_path = ltrim( str_replace( static::$dir, '', Utils\normalize_path( $file ) ), '/' );
+			$relative_file_path = ltrim( str_replace( static::$dir, '', Path::normalize( $file ) ), '/' );
 
 			// Make sure a relative file path is added as a comment.
 			$options['file'] = $relative_file_path;
@@ -121,24 +126,26 @@ public static function fromFile( $file_or_files, Translations $translations, arr
 
 			static::fromString( $text, $translations, $options );
 		}
+
+		return null;
 	}
 
 	/**
 	 * Extract the translations from a file.
 	 *
-	 * @param string $dir                Root path to start the recursive traversal in.
-	 * @param Translations $translations The translations instance to append the new translations.
-	 * @param array        $options      {
+	 * @param string               $dir                Root path to start the recursive traversal in.
+	 * @param Translations         $translations The translations instance to append the new translations.
+	 * @param array<string, mixed> $options      {
 	 *     Optional. An array of options passed down to static::fromString()
 	 *
 	 *     @type bool $wpExtractTemplates Extract 'Template Name' headers in theme files. Default 'false'.
-	 *     @type array $exclude           A list of path to exclude. Default [].
-	 *     @type array $extensions        A list of extensions to process. Default [].
+	 *     @type array<string> $exclude           A list of path to exclude. Default [].
+	 *     @type array<string> $extensions        A list of extensions to process. Default [].
 	 * }
 	 * @return void
 	 */
 	public static function fromDirectory( $dir, Translations $translations, array $options = [] ) {
-		$dir = Utils\normalize_path( $dir );
+		$dir = Path::normalize( $dir );
 
 		static::$dir = $dir;
 
@@ -157,8 +164,8 @@ public static function fromDirectory( $dir, Translations $translations, array $o
 	/**
 	 * Determines whether a file is valid based on given matchers.
 	 *
-	 * @param SplFileInfo $file     File or directory.
-	 * @param array       $matchers List of files and directories to match.
+	 * @param SplFileInfo   $file     File or directory.
+	 * @param array<string> $matchers List of files and directories to match.
 	 * @return int How strongly the file is matched.
 	 */
 	protected static function calculateMatchScore( SplFileInfo $file, array $matchers = [] ) {
@@ -211,8 +218,8 @@ static function ( $component ) {
 	/**
 	 * Determines whether or not a directory has children that may be matched.
 	 *
-	 * @param SplFileInfo $dir      Directory.
-	 * @param array       $matchers List of files and directories to match.
+	 * @param SplFileInfo   $dir      Directory.
+	 * @param array<string> $matchers List of files and directories to match.
 	 * @return bool Whether or not there are any matchers for children of this directory.
 	 */
 	protected static function containsMatchingChildren( SplFileInfo $dir, array $matchers = [] ) {
@@ -252,12 +259,12 @@ protected static function containsMatchingChildren( SplFileInfo $dir, array $mat
 	/**
 	 * Recursively gets all PHP files within a directory.
 	 *
-	 * @param string $dir A path of a directory.
-	 * @param array $includes List of files and directories to include.
-	 * @param array $excludes List of files and directories to skip.
-	 * @param array $extensions List of filename extensions to process.
+	 * @param string        $dir A path of a directory.
+	 * @param array<string> $includes List of files and directories to include.
+	 * @param array<string> $excludes List of files and directories to skip.
+	 * @param array<string> $extensions List of filename extensions to process.
 	 *
-	 * @return array File list.
+	 * @return array<string> File list.
 	 */
 	public static function getFilesFromDirectory( $dir, array $includes = [], array $excludes = [], $extensions = [] ) {
 		$filtered_files = [];
@@ -308,7 +315,7 @@ static function ( $file, $key, $iterator ) use ( $includes, $excludes, $extensio
 				continue;
 			}
 
-			$filtered_files[] = Utils\normalize_path( $file->getPathname() );
+			$filtered_files[] = Path::normalize( $file->getPathname() );
 		}
 
 		sort( $filtered_files, SORT_NATURAL | SORT_FLAG_CASE );
@@ -320,8 +327,8 @@ static function ( $file, $key, $iterator ) use ( $includes, $excludes, $extensio
 	 * Determines whether the file extension of a file matches any of the given file extensions.
 	 * The end/last part of a multi file extension must also match (`js` of `min.js`).
 	 *
-	 * @param SplFileInfo $file       File or directory.
-	 * @param array       $extensions List of file extensions to match.
+	 * @param SplFileInfo   $file       File or directory.
+	 * @param array<string> $extensions List of file extensions to match.
 	 * @return bool Whether the file has a file extension that matches any of the ones in the list.
 	 */
 	protected static function file_has_file_extension( $file, $extensions ) {
diff --git a/src/JedGenerator.php b/src/JedGenerator.php
index 7665a42..80224ed 100644
--- a/src/JedGenerator.php
+++ b/src/JedGenerator.php
@@ -14,6 +14,10 @@
 class JedGenerator extends Jed {
 	/**
 	 * {@parentDoc}.
+	 *
+	 * @param Translations $translations Translations instance.
+	 * @param array<mixed> $options      Options.
+	 * @return string
 	 */
 	public static function toString( Translations $translations, array $options = [] ) {
 		$options += static::$options;
@@ -38,15 +42,16 @@ public static function toString( Translations $translations, array $options = []
 			],
 		];
 
-		return json_encode( $data, $options['json'] );
+		$result = json_encode( $data, $options['json'] );
+		return false === $result ? '' : $result;
 	}
 
 	/**
 	 * Generates an array with all translations.
 	 *
-	 * @param Translations $translations
+	 * @param Translations $translations Translations instance.
 	 *
-	 * @return array
+	 * @return array<string, array<string>>
 	 */
 	public static function buildMessages( Translations $translations ) {
 		$plural_forms      = $translations->getPluralForms();
diff --git a/src/JsCodeExtractor.php b/src/JsCodeExtractor.php
index 4c03ee5..3460a30 100644
--- a/src/JsCodeExtractor.php
+++ b/src/JsCodeExtractor.php
@@ -11,6 +11,9 @@
 final class JsCodeExtractor extends JsCode {
 	use IterableCodeExtractor;
 
+	/**
+	 * @var array<mixed>
+	 */
 	public static $options = [
 		'extractComments' => [ 'translators', 'Translators' ],
 		'constants'       => [],
@@ -22,10 +25,18 @@ final class JsCodeExtractor extends JsCode {
 		],
 	];
 
+	/**
+	 * @var string
+	 */
 	protected static $functionsScannerClass = 'WP_CLI\I18n\JsFunctionsScanner';
 
 	/**
-	 * @inheritdoc
+	 * {@inheritdoc}
+	 *
+	 * @param string       $text         The text to extract strings from.
+	 * @param Translations $translations Translations instance.
+	 * @param array<mixed> $options      Extraction options.
+	 * @return void
 	 */
 	public static function fromString( $text, Translations $translations, array $options = [] ) {
 		WP_CLI::debug( "Parsing file {$options['file']}", 'make-pot' );
@@ -56,7 +67,12 @@ public static function fromString( $text, Translations $translations, array $opt
 	}
 
 	/**
-	 * @inheritDoc
+	 * {@inheritdoc}
+	 *
+	 * @param string               $text         The text to extract strings from.
+	 * @param array<\Gettext\Translations> $translations Translations instances.
+	 * @param array<mixed>         $options      Extraction options.
+	 * @return void
 	 */
 	public static function fromStringMultiple( $text, array $translations, array $options = [] ) {
 		$options += self::$options;
@@ -64,6 +80,9 @@ public static function fromStringMultiple( $text, array $translations, array $op
 		/** @var JsFunctionsScanner $functions */
 		$functions = new self::$functionsScannerClass( $text );
 		$functions->enableCommentsExtraction( $options['extractComments'] );
-		$functions->saveGettextFunctions( $translations, $options );
+
+		if ( ! empty( $translations ) ) {
+			$functions->saveGettextFunctions( $translations[0], $options );
+		}
 	}
 }
diff --git a/src/JsFunctionsScanner.php b/src/JsFunctionsScanner.php
index 97fa25d..0ca6890 100644
--- a/src/JsFunctionsScanner.php
+++ b/src/JsFunctionsScanner.php
@@ -13,7 +13,7 @@ final class JsFunctionsScanner extends GettextJsFunctionsScanner {
 	/**
 	 * If not false, comments will be extracted.
 	 *
-	 * @var string|false|array
+	 * @var string|false|array<string>
 	 */
 	private $extract_comments = false;
 
@@ -29,7 +29,8 @@ final class JsFunctionsScanner extends GettextJsFunctionsScanner {
 	/**
 	 * Enable extracting comments that start with a tag (if $tag is empty all the comments will be extracted).
 	 *
-	 * @param mixed $tag
+	 * @param string|array<string> $tag Tag to extract.
+	 * @return void
 	 */
 	public function enableCommentsExtraction( $tag = '' ) {
 		$this->extract_comments = $tag;
@@ -37,6 +38,8 @@ public function enableCommentsExtraction( $tag = '' ) {
 
 	/**
 	 * Disable comments extraction.
+	 *
+	 * @return void
 	 */
 	public function disableCommentsExtraction() {
 		$this->extract_comments = false;
@@ -44,6 +47,10 @@ public function disableCommentsExtraction() {
 
 	/**
 	 * {@inheritdoc}
+	 *
+	 * @param \Gettext\Translations $translations Translations instance.
+	 * @param array<mixed>         $options      Options.
+	 * @return void
 	 */
 	public function saveGettextFunctions( $translations, array $options ) {
 		// Ignore multiple translations for now.
@@ -75,13 +82,12 @@ function ( $node ) use ( &$translations, $options, &$all_comments ) {
 				$file          = $options['file'];
 				$add_reference = ! empty( $options['addReferences'] );
 
-				/** @var Node\Node $node */
 				foreach ( $node->getLeadingComments() as $comment ) {
 					$all_comments[] = $comment;
 				}
 
 				/** @var Node\CallExpression $node */
-				if ( 'CallExpression' !== $node->getType() ) {
+				if ( ! $node instanceof Node\CallExpression ) {
 					return;
 				}
 
@@ -91,7 +97,6 @@ function ( $node ) use ( &$translations, $options, &$all_comments ) {
 					return;
 				}
 
-				/** @var Node\CallExpression $node */
 				foreach ( $node->getArguments() as $argument ) {
 					// Support nested function calls.
 					$argument->setLeadingComments( $argument->getLeadingComments() + $node->getLeadingComments() );
@@ -107,7 +112,6 @@ function ( $node ) use ( &$translations, $options, &$all_comments ) {
 				$plural   = null;
 				$args     = [];
 
-				/** @var Node\Node $argument */
 				foreach ( $node->getArguments() as $argument ) {
 					foreach ( $argument->getLeadingComments() as $comment ) {
 						$all_comments[] = $comment;
@@ -121,13 +125,13 @@ function ( $node ) use ( &$translations, $options, &$all_comments ) {
 						continue;
 					}
 
-					if ( 'Literal' === $argument->getType() ) {
+					if ( $argument instanceof Node\Literal ) {
 						/** @var Node\Literal $argument */
 						$args[] = $argument->getValue();
 						continue;
 					}
 
-					if ( 'TemplateLiteral' === $argument->getType() && 0 === count( $argument->getExpressions() ) ) {
+					if ( $argument instanceof Node\TemplateLiteral && 0 === count( $argument->getExpressions() ) ) {
 						/** @var Node\TemplateLiteral $argument */
 						/** @var Node\TemplateElement[] $parts */
 
@@ -233,7 +237,6 @@ function ( $node ) use ( &$translations, $options, $scanner ) {
 				}
 
 				$eval_contents = '';
-				/** @var Node\Node $argument */
 				foreach ( $node->getArguments() as $argument ) {
 					if ( 'Literal' === $argument->getType() ) {
 						/** @var Node\Literal $argument */
@@ -264,14 +267,14 @@ function ( $node ) use ( &$translations, $options, $scanner ) {
 	 *
 	 * @param Node\CallExpression $node The call expression whose callee to resolve.
 	 *
-	 * @return array|bool Array containing the name and comments of the identifier if resolved. False if not.
+	 * @return array<string, mixed>|bool Array containing the name and comments of the identifier if resolved. False if not.
 	 */
 	private function resolveExpressionCallee( Node\CallExpression $node ) {
 		$callee = $node->getCallee();
 
 		// If the callee is a simple identifier it can simply be returned.
 		// For example: __( "translation" ).
-		if ( 'Identifier' === $callee->getType() ) {
+		if ( $callee instanceof Node\Identifier ) {
 			return [
 				'name'     => $callee->getName(),
 				'comments' => $callee->getLeadingComments(),
@@ -281,11 +284,11 @@ private function resolveExpressionCallee( Node\CallExpression $node ) {
 		// If the callee is a member expression resolve it to the property.
 		// For example: wp.i18n.__( "translation" ) or u.__( "translation" ).
 		if (
-			'MemberExpression' === $callee->getType() &&
-			'Identifier' === $callee->getProperty()->getType()
+			$callee instanceof Node\MemberExpression &&
+			$callee->getProperty() instanceof Node\Identifier
 		) {
 			// Make sure to unpack wp.i18n which is a nested MemberExpression.
-			$comments = 'MemberExpression' === $callee->getObject()->getType()
+			$comments = $callee->getObject() instanceof Node\MemberExpression
 				? $callee->getObject()->getObject()->getLeadingComments()
 				: $callee->getObject()->getLeadingComments();
 
@@ -298,16 +301,16 @@ private function resolveExpressionCallee( Node\CallExpression $node ) {
 		// If the callee is a call expression as created by Webpack resolve it.
 		// For example: Object(u.__)( "translation" ).
 		if (
-			'CallExpression' === $callee->getType() &&
-			'Identifier' === $callee->getCallee()->getType() &&
+			$callee instanceof Node\CallExpression &&
+			$callee->getCallee() instanceof Node\Identifier &&
 			'Object' === $callee->getCallee()->getName() &&
 			[] !== $callee->getArguments() &&
-			'MemberExpression' === $callee->getArguments()[0]->getType()
+			$callee->getArguments()[0] instanceof Node\MemberExpression
 		) {
 			$property = $callee->getArguments()[0]->getProperty();
 
 			// Matches minified webpack statements: Object(u.__)( "translation" ).
-			if ( 'Identifier' === $property->getType() ) {
+			if ( $property instanceof Node\Identifier ) {
 				return [
 					'name'     => $property->getName(),
 					'comments' => $callee->getCallee()->getLeadingComments(),
@@ -316,7 +319,7 @@ private function resolveExpressionCallee( Node\CallExpression $node ) {
 
 			// Matches unminified webpack statements:
 			// Object(_wordpress_i18n__WEBPACK_IMPORTED_MODULE_7__["__"])( "translation" );
-			if ( 'Literal' === $property->getType() ) {
+			if ( $property instanceof Node\Literal ) {
 				$name = $property->getValue();
 
 				// Matches mangled webpack statement:
@@ -336,14 +339,14 @@ private function resolveExpressionCallee( Node\CallExpression $node ) {
 		// If the callee is an indirect function call as created by babel, resolve it.
 		// For example: `(0, u.__)( "translation" )`.
 		if (
-			'ParenthesizedExpression' === $callee->getType()
-			&& 'SequenceExpression' === $callee->getExpression()->getType()
+			$callee instanceof Node\ParenthesizedExpression
+			&& $callee->getExpression() instanceof Node\SequenceExpression
 			&& 2 === count( $callee->getExpression()->getExpressions() )
-			&& 'Literal' === $callee->getExpression()->getExpressions()[0]->getType()
+			&& $callee->getExpression()->getExpressions()[0] instanceof Node\Literal
 			&& [] !== $node->getArguments()
 		) {
 			// Matches any general indirect function call: `(0, __)( "translation" )`.
-			if ( 'Identifier' === $callee->getExpression()->getExpressions()[1]->getType() ) {
+			if ( $callee->getExpression()->getExpressions()[1] instanceof Node\Identifier ) {
 				return [
 					'name'     => $callee->getExpression()->getExpressions()[1]->getName(),
 					'comments' => $callee->getLeadingComments(),
@@ -351,10 +354,10 @@ private function resolveExpressionCallee( Node\CallExpression $node ) {
 			}
 
 			// Matches indirect function calls used by babel for module imports: `(0, _i18n.__)( "translation" )`.
-			if ( 'MemberExpression' === $callee->getExpression()->getExpressions()[1]->getType() ) {
+			if ( $callee->getExpression()->getExpressions()[1] instanceof Node\MemberExpression ) {
 				$property = $callee->getExpression()->getExpressions()[1]->getProperty();
 
-				if ( 'Identifier' === $property->getType() ) {
+				if ( $property instanceof Node\Identifier ) {
 					return [
 						'name'     => $property->getName(),
 						'comments' => $callee->getLeadingComments(),
diff --git a/src/JsonSchemaExtractor.php b/src/JsonSchemaExtractor.php
index 63ae0f5..0ed0fa9 100644
--- a/src/JsonSchemaExtractor.php
+++ b/src/JsonSchemaExtractor.php
@@ -80,7 +80,12 @@ protected static function load_schema( $schema, $fallback ) {
 	}
 
 	/**
-	 * @inheritdoc
+	 * {@inheritdoc}
+	 *
+	 * @param string       $text         The text to extract strings from.
+	 * @param Translations $translations Translations instance.
+	 * @param array<mixed> $options      Extraction options.
+	 * @return void
 	 */
 	public static function fromString( $text, Translations $translations, array $options = [] ) {
 		$file = $options['file'];
@@ -114,10 +119,10 @@ public static function fromString( $text, Translations $translations, array $opt
 	/**
 	 * Extract strings from a JSON file using its i18n schema.
 	 *
-	 * @param Translations                   $translations The translations instance to append the new translations.
-	 * @param string|null                    $file         JSON file name or null if no reference should be added.
-	 * @param string|string[]|array[]|object $i18n_schema  I18n schema for the setting.
-	 * @param string|string[]|array[]        $settings     Value for the settings.
+	 * @param Translations         $translations The translations instance to append the new translations.
+	 * @param string|null          $file         JSON file name or null if no reference should be added.
+	 * @param mixed                $i18n_schema  I18n schema for the setting.
+	 * @param mixed                $settings     Value for the settings.
 	 *
 	 * @return void
 	 */
diff --git a/src/MakeJsonCommand.php b/src/MakeJsonCommand.php
index b52c9a2..b5c8bb5 100644
--- a/src/MakeJsonCommand.php
+++ b/src/MakeJsonCommand.php
@@ -67,6 +67,10 @@ class MakeJsonCommand extends WP_CLI_Command {
 	 *     # Create JSON files with object mapping
 	 *     $ wp i18n make-json languages '--use-map={"source/index.js":"build/index.js"}'
 	 *
+	 * @param array<string> $args       Command arguments.
+	 * @param array<mixed>  $assoc_args Associative arguments.
+	 * @return void
+	 *
 	 * @when before_wp_load
 	 *
 	 * @throws WP_CLI\ExitException
@@ -129,8 +133,8 @@ function ( $extension ) {
 	/**
 	 * Collect maps from paths, normalize and merge
 	 *
-	 * @param string|array|bool $paths_or_maps argument. False to do nothing.
-	 * @return array|null       Mapping array. Null if no maps specified.
+	 * @param string|array<mixed>|bool $paths_or_maps argument. False to do nothing.
+	 * @return array<string, mixed>|null Mapping array. Null if no maps specified.
 	 */
 	protected function build_map( $paths_or_maps ) {
 		if ( false === $paths_or_maps ) {
@@ -204,12 +208,12 @@ static function ( $value ) {
 	/**
 	 * Splits a single PO file into multiple JSON files.
 	 *
-	 * @param string     $source_file Path to the source file.
-	 * @param string     $destination Path to the destination directory.
-	 * @param array|null $map         Source to build file mapping.
-	 * @param string     $domain      Override text domain to use.
-	 * @param array      $extensions  Additional extensions.
-	 * @return array     List of created JSON files.
+	 * @param string                    $source_file Path to the source file.
+	 * @param string                    $destination Path to the destination directory.
+	 * @param array<string, mixed>|null $map         Source to build file mapping.
+	 * @param string                    $domain      Override text domain to use.
+	 * @param array<string>             $extensions  Additional extensions.
+	 * @return array<string>     List of created JSON files.
 	 */
 	protected function make_json( $source_file, $destination, $map, $domain, $extensions ) {
 		/** @var Translations[] $mapping */
@@ -277,9 +281,9 @@ static function ( $reference ) use ( $extensions ) {
 	/**
 	 * Takes the references and applies map, if given
 	 *
-	 * @param array      $references translation references
-	 * @param array|null $map file mapping
-	 * @return array     mapped references
+	 * @param array<mixed>              $references translation references
+	 * @param array<string, mixed>|null $map file mapping
+	 * @return array<mixed>     mapped references
 	 */
 	protected function reference_map( $references, $map ) {
 		if ( is_null( $map ) ) {
@@ -321,11 +325,11 @@ static function ( $value ) {
 	 *
 	 * Exports translations for each JS file to a separate translation file.
 	 *
-	 * @param array  $mapping        A mapping of files to translation entries.
-	 * @param string $base_file_name Base file name for JSON files.
-	 * @param string $destination    Path to the destination directory.
+	 * @param array<string, \Gettext\Translations> $mapping        A mapping of files to translation entries.
+	 * @param string                              $base_file_name Base file name for JSON files.
+	 * @param string                              $destination    Path to the destination directory.
 	 *
-	 * @return array List of created JSON files.
+	 * @return array<string> List of created JSON files.
 	 */
 	protected function build_json_files( $mapping, $base_file_name, $destination ) {
 		$result = [];
diff --git a/src/MakeMoCommand.php b/src/MakeMoCommand.php
index 2a0057c..5838e5d 100644
--- a/src/MakeMoCommand.php
+++ b/src/MakeMoCommand.php
@@ -35,6 +35,10 @@ class MakeMoCommand extends WP_CLI_Command {
 	 *     # Create a MO file from a single PO file to a specific file destination
 	 *     $ wp i18n make-mo example-plugin-de_DE.po languages/bar.mo
 	 *
+	 * @param array<string> $args       Command arguments.
+	 * @param array<mixed>  $assoc_args Associative arguments.
+	 * @return void
+	 *
 	 * @when before_wp_load
 	 *
 	 * @throws WP_CLI\ExitException
diff --git a/src/MakePhpCommand.php b/src/MakePhpCommand.php
index baeed19..f9dfd33 100644
--- a/src/MakePhpCommand.php
+++ b/src/MakePhpCommand.php
@@ -41,6 +41,10 @@ class MakePhpCommand extends WP_CLI_Command {
 	 *     $ wp i18n make-php example-plugin-de_DE.po languages --pretty-print
 	 *     Success: Created 1 file.
 	 *
+	 * @param array<string> $args       Command arguments.
+	 * @param array<mixed>  $assoc_args Associative arguments.
+	 * @return void
+	 *
 	 * @when before_wp_load
 	 *
 	 * @throws WP_CLI\ExitException
diff --git a/src/MakePotCommand.php b/src/MakePotCommand.php
index 3d14245..599c824 100644
--- a/src/MakePotCommand.php
+++ b/src/MakePotCommand.php
@@ -9,7 +9,9 @@
 use Gettext\Utils\ParsedComment;
 use WP_CLI;
 use WP_CLI_Command;
+use WP_CLI\Path;
 use WP_CLI\Utils;
+
 use DirectoryIterator;
 use IteratorIterator;
 
@@ -25,7 +27,7 @@ class MakePotCommand extends WP_CLI_Command {
 	protected $destination;
 
 	/**
-	 * @var array
+	 * @var array<string>
 	 */
 	protected $merge = [];
 
@@ -40,12 +42,12 @@ class MakePotCommand extends WP_CLI_Command {
 	protected $subtract_and_merge;
 
 	/**
-	 * @var array
+	 * @var array<string>
 	 */
 	protected $include = [];
 
 	/**
-	 * @var array
+	 * @var array<string>
 	 */
 	protected $exclude = [ 'node_modules', '.*', 'vendor', 'Gruntfile.js', 'webpack.config.js', '*.min.js', 'test', 'tests' ];
 
@@ -55,7 +57,7 @@ class MakePotCommand extends WP_CLI_Command {
 	protected $slug;
 
 	/**
-	 * @var array
+	 * @var array<string, mixed>
 	 */
 	protected $main_file_data = [];
 
@@ -100,7 +102,7 @@ class MakePotCommand extends WP_CLI_Command {
 	protected $location = true;
 
 	/**
-	 * @var array
+	 * @var array<string, mixed>
 	 */
 	protected $headers = [];
 
@@ -115,9 +117,9 @@ class MakePotCommand extends WP_CLI_Command {
 	protected $package_name;
 
 	/**
-	 * @var string
+	 * @var string|null
 	 */
-	protected $file_comment;
+	protected $file_comment = null;
 
 	/**
 	 * @var string
@@ -282,6 +284,10 @@ class MakePotCommand extends WP_CLI_Command {
 	 *     # Create a POT file for the WordPress theme in the current directory with custom headers.
 	 *     $ wp i18n make-pot . languages/my-theme.pot --headers='{"Report-Msgid-Bugs-To":"https://github.com/theme-author/my-theme/","POT-Creation-Date":""}'
 	 *
+	 * @param array<string> $args       Command arguments.
+	 * @param array<mixed>  $assoc_args Associative arguments.
+	 * @return void
+	 *
 	 * @when before_wp_load
 	 *
 	 * @throws WP_CLI\ExitException
@@ -315,25 +321,29 @@ public function __invoke( $args, $assoc_args ) {
 	 *
 	 * @throws WP_CLI\ExitException
 	 *
-	 * @param array $args       Command arguments.
-	 * @param array $assoc_args Associative arguments.
+	 * @param array<string> $args       Command arguments.
+	 * @param array<mixed>  $assoc_args Associative arguments.
+	 * @return void
 	 */
 	public function handle_arguments( $args, $assoc_args ) {
 		$array_arguments = array( 'headers' );
 		$assoc_args      = Utils\parse_shell_arrays( $assoc_args, $array_arguments );
 
 		$this->source          = realpath( $args[0] );
-		$this->slug            = Utils\get_flag_value( $assoc_args, 'slug', Utils\basename( $this->source ) );
+		$this->slug            = Utils\get_flag_value( $assoc_args, 'slug', Path::basename( $this->source ) );
 		$this->skip_js         = Utils\get_flag_value( $assoc_args, 'skip-js', $this->skip_js );
 		$this->skip_php        = Utils\get_flag_value( $assoc_args, 'skip-php', $this->skip_php );
 		$this->skip_blade      = Utils\get_flag_value( $assoc_args, 'skip-blade', $this->skip_blade );
 		$this->skip_block_json = Utils\get_flag_value( $assoc_args, 'skip-block-json', $this->skip_block_json );
 		$this->skip_theme_json = Utils\get_flag_value( $assoc_args, 'skip-theme-json', $this->skip_theme_json );
 		$this->skip_audit      = Utils\get_flag_value( $assoc_args, 'skip-audit', $this->skip_audit );
-		$this->headers         = Utils\get_flag_value( $assoc_args, 'headers', $this->headers );
-		$this->file_comment    = Utils\get_flag_value( $assoc_args, 'file-comment' );
-		$this->package_name    = Utils\get_flag_value( $assoc_args, 'package-name' );
-		$this->location        = Utils\get_flag_value( $assoc_args, 'location', true );
+		$headers               = Utils\get_flag_value( $assoc_args, 'headers', null );
+		if ( null !== $headers ) {
+			$this->headers = (array) $headers; // Cast to array if single string given
+		}
+		$this->file_comment = Utils\get_flag_value( $assoc_args, 'file-comment' );
+		$this->package_name = Utils\get_flag_value( $assoc_args, 'package-name' );
+		$this->location     = Utils\get_flag_value( $assoc_args, 'location', true );
 
 		$ignore_domain = Utils\get_flag_value( $assoc_args, 'ignore-domain', false );
 
@@ -462,7 +472,7 @@ protected function unslashit( $text ) {
 	/**
 	 * Retrieves the main file data of the plugin or theme.
 	 *
-	 * @return array
+	 * @return array<string, mixed>
 	 */
 	protected function get_main_file_data() {
 		$files = new IteratorIterator( new DirectoryIterator( $this->source ) );
@@ -546,7 +556,7 @@ protected function get_main_file_data() {
 	 *
 	 * @param string $type Source type, either theme or plugin.
 	 *
-	 * @return array List of file headers.
+	 * @return array<string> List of file headers.
 	 */
 	protected function get_file_headers( $type ) {
 		switch ( $type ) {
@@ -629,7 +639,7 @@ protected function extract_strings() {
 			}
 
 			if ( $this->main_file_path && $this->location ) {
-				$file_reference = ltrim( str_replace( Utils\normalize_path( "$this->source/" ), '', Utils\normalize_path( $this->main_file_path ) ), '/' );
+				$file_reference = ltrim( str_replace( Path::normalize( "$this->source/" ), '', Path::normalize( $this->main_file_path ) ), '/' );
 				// Add line number if available
 				if ( ! empty( $data['line'] ) ) {
 					$translation->addReference( $file_reference, $data['line'] );
@@ -777,7 +787,8 @@ protected function extract_strings() {
 	 *
 	 * Goes through all extracted strings to find possible mistakes.
 	 *
-	 * @param Translations $translations Translations object.
+	 * @param \Gettext\Translations $translations Translations object.
+	 * @return void
 	 */
 	protected function audit_strings( $translations ) {
 		foreach ( $translations as $translation ) {
@@ -809,8 +820,6 @@ protected function audit_strings( $translations ) {
 				$comments = array_filter(
 					$comments,
 					function ( $comment ) {
-						/** @var ParsedComment|string $comment */
-						/** @var string $file_header */
 						foreach ( $this->get_file_headers( $this->project_type ) as $file_header ) {
 							if ( 0 === strpos( ( $comment instanceof ParsedComment ? $comment->getComment() : $comment ), $file_header ) ) {
 								return null;
@@ -829,12 +838,12 @@ function ( $comment ) {
 					function ( $comment ) use ( &$unique_comments ) {
 						/** @var ParsedComment|string $comment */
 						if ( in_array( ( $comment instanceof ParsedComment ? $comment->getComment() : $comment ), $unique_comments, true ) ) {
-							return null;
+							return false;
 						}
 
 						$unique_comments[] = ( $comment instanceof ParsedComment ? $comment->getComment() : $comment );
 
-						return $comment;
+						return true;
 					}
 				);
 
@@ -965,7 +974,8 @@ protected function get_file_comment() {
 	/**
 	 * Sets default POT file headers for the project.
 	 *
-	 * @param Translations $translations Translations object.
+	 * @param \Gettext\Translations $translations Translations object.
+	 * @return void
 	 */
 	protected function set_default_headers( $translations ) {
 		$name         = null;
diff --git a/src/MapCodeExtractor.php b/src/MapCodeExtractor.php
index 7a38a77..1d0c56d 100644
--- a/src/MapCodeExtractor.php
+++ b/src/MapCodeExtractor.php
@@ -10,6 +10,9 @@
 final class MapCodeExtractor extends JsCode {
 	use IterableCodeExtractor;
 
+	/**
+	 * @var array<mixed>
+	 */
 	public static $options = [
 		'extractComments' => [ 'translators', 'Translators' ],
 		'constants'       => [],
@@ -23,6 +26,11 @@ final class MapCodeExtractor extends JsCode {
 
 	/**
 	 * {@inheritdoc}
+	 *
+	 * @param string       $text
+	 * @param Translations $translations
+	 * @param array<mixed> $options
+	 * @return void
 	 */
 	public static function fromString( $text, Translations $translations, array $options = [] ) {
 		if ( ! array_key_exists( 'file', $options ) || substr( $options['file'], -7 ) !== '.js.map' ) {
diff --git a/src/PhpArrayGenerator.php b/src/PhpArrayGenerator.php
index ddfc824..c2f46e5 100644
--- a/src/PhpArrayGenerator.php
+++ b/src/PhpArrayGenerator.php
@@ -12,6 +12,9 @@
  * Returns output in the form WordPress uses.
  */
 class PhpArrayGenerator extends PhpArray {
+	/**
+	 * @var array<string, bool>
+	 */
 	public static $options = [
 		'includeHeaders' => false,
 		'prettyPrint'    => false,
@@ -19,21 +22,24 @@ class PhpArrayGenerator extends PhpArray {
 
 	/**
 	 * {@inheritdoc}
+	 *
+	 * @param array<mixed> $options
+	 * @return string
 	 */
 	public static function toString( Translations $translations, array $options = [] ) {
 		$options = array_merge( static::$options, $options );
 		$array   = static::generate( $translations, $options );
 
-		return '<?php' . PHP_EOL . 'return ' . static::var_export( $array, $options['prettyPrint'] ) . ';';
+		return '<?php' . PHP_EOL . 'return ' . self::var_export( $array, $options['prettyPrint'] ) . ';';
 	}
 
 	/**
 	 * Generates an array with the translations.
 	 *
 	 * @param Translations $translations
-	 * @param array        $options
+	 * @param array<mixed> $options
 	 *
-	 * @return array
+	 * @return array<string, mixed>
 	 */
 	public static function generate( Translations $translations, array $options = [] ) {
 		$options += static::$options;
@@ -48,7 +54,7 @@ public static function generate( Translations $translations, array $options = []
 	 * @param bool         $include_headers
 	 * @param bool         $force_array Unused.
 	 *
-	 * @return array
+	 * @return array<string, mixed>
 	 */
 	protected static function toArray( Translations $translations, $include_headers, $force_array = false ) {
 		$messages = [];
diff --git a/src/PhpCodeExtractor.php b/src/PhpCodeExtractor.php
index 6014848..e5aea3c 100644
--- a/src/PhpCodeExtractor.php
+++ b/src/PhpCodeExtractor.php
@@ -10,6 +10,9 @@
 final class PhpCodeExtractor extends PhpCode {
 	use IterableCodeExtractor;
 
+	/**
+	 * @var array<mixed>
+	 */
 	public static $options = [
 		'extractComments' => [ 'translators', 'Translators' ],
 		'constants'       => [],
@@ -43,10 +46,18 @@ final class PhpCodeExtractor extends PhpCode {
 		],
 	];
 
+	/**
+	 * @var string
+	 */
 	protected static $functionsScannerClass = 'WP_CLI\I18n\PhpFunctionsScanner';
 
 	/**
 	 * {@inheritdoc}
+	 *
+	 * @param string       $text
+	 * @param Translations $translations
+	 * @param array<mixed> $options
+	 * @return void
 	 */
 	public static function fromString( $text, Translations $translations, array $options = [] ) {
 		WP_CLI::debug( "Parsing file {$options['file']}", 'make-pot' );
diff --git a/src/PhpFunctionsScanner.php b/src/PhpFunctionsScanner.php
index 033ba2d..b770823 100644
--- a/src/PhpFunctionsScanner.php
+++ b/src/PhpFunctionsScanner.php
@@ -8,6 +8,10 @@ class PhpFunctionsScanner extends GettextPhpFunctionsScanner {
 
 	/**
 	 * {@inheritdoc}
+	 *
+	 * @param \Gettext\Translations $translations Translations instance.
+	 * @param array<mixed>         $options      Options.
+	 * @return void
 	 */
 	public function saveGettextFunctions( $translations, array $options ) {
 		// Ignore multiple translations for now.
diff --git a/src/PotGenerator.php b/src/PotGenerator.php
index ed2f9a5..f3d207d 100644
--- a/src/PotGenerator.php
+++ b/src/PotGenerator.php
@@ -13,6 +13,9 @@
  * adds some comments at the very beginning of the file.
  */
 class PotGenerator extends PoGenerator {
+	/**
+	 * @var array<string>
+	 */
 	protected static $comments_before_headers = [];
 
 	/**
@@ -21,6 +24,7 @@ class PotGenerator extends PoGenerator {
 	 * Doesn't need to include # in the beginning of lines, these are added automatically.
 	 *
 	 * @param string $comment File comment.
+	 * @return void
 	 */
 	public static function setCommentBeforeHeaders( $comment ) {
 		$comments = explode( "\n", $comment );
@@ -33,7 +37,11 @@ public static function setCommentBeforeHeaders( $comment ) {
 	}
 
 	/**
-	 * {@parentDoc}.
+	 * {@inheritdoc}
+	 *
+	 * @param \Gettext\Translations $translations
+	 * @param array<mixed>         $options
+	 * @return string
 	 */
 	public static function toString( Translations $translations, array $options = [] ) {
 		$lines   = static::$comments_before_headers;
@@ -109,7 +117,7 @@ public static function toString( Translations $translations, array $options = []
 	 *
 	 * @return string[]
 	 */
-	protected static function multilineQuote( $text ) {
+	protected static function wpMultilineQuote( $text ) {
 		$lines = explode( "\n", $text );
 		$last  = count( $lines ) - 1;
 
@@ -127,12 +135,13 @@ protected static function multilineQuote( $text ) {
 	/**
 	 * Add one or more lines depending whether the string is multiline or not.
 	 *
-	 * @param array  &$lines Array lines should be added to.
-	 * @param string $name   Name of the line, e.g. msgstr or msgid_plural.
-	 * @param string $value  The line to add.
+	 * @param array<mixed> &$lines Array lines should be added to.
+	 * @param string        $name   Name of the line, e.g. msgstr or msgid_plural.
+	 * @param string        $value  The line to add.
+	 * @return void
 	 */
 	protected static function addLines( array &$lines, $name, $value ) {
-		$newlines = self::multilineQuote( $value );
+		$newlines = self::wpMultilineQuote( $value );
 
 		if ( count( $newlines ) === 1 ) {
 			$lines[] = $name . ' ' . $newlines[0];
diff --git a/src/UpdatePoCommand.php b/src/UpdatePoCommand.php
index faa8f02..fa77c97 100644
--- a/src/UpdatePoCommand.php
+++ b/src/UpdatePoCommand.php
@@ -55,6 +55,9 @@ class UpdatePoCommand extends WP_CLI_Command {
 	 *
 	 * @when before_wp_load
 	 *
+	 * @param array<string>        $args       Positional arguments.
+	 * @param array<string, mixed> $assoc_args Associative arguments.
+	 * @return void
 	 * @throws WP_CLI\ExitException
 	 */
 	public function __invoke( $args, $assoc_args ) {
diff --git a/stubs/Gettext.stub b/stubs/Gettext.stub
new file mode 100644
index 0000000..f4799b5
--- /dev/null
+++ b/stubs/Gettext.stub
@@ -0,0 +1,36 @@
+<?php
+
+namespace Gettext\Extractors {
+	abstract class PhpCode {
+		/**
+		 * @var array<mixed>
+		 */
+		public static $options;
+
+		/**
+		 * @var string
+		 */
+		protected static $functionsScannerClass;
+	}
+
+	abstract class JsCode {
+		/**
+		 * @var array<mixed>
+		 */
+		public static $options;
+
+		/**
+		 * @var string
+		 */
+		protected static $functionsScannerClass;
+	}
+}
+
+namespace Gettext\Generators {
+	class PhpArray {
+		/**
+		 * @var array<string, bool>
+		 */
+		public $options;
+	}
+}
diff --git a/tests/phpstan/scan-files.php b/tests/phpstan/scan-files.php
new file mode 100644
index 0000000..665af52
--- /dev/null
+++ b/tests/phpstan/scan-files.php
@@ -0,0 +1,16 @@
+<?php
+// phpcs:ignoreFile
+
+namespace {
+
+	define( 'WP_CLI_VERSION', '2.x.x' );
+
+	class Requests_Response {
+		/** @var bool */
+		public $success;
+		/** @var int */
+		public $status_code;
+		/** @var string */
+		public $body;
+	}
+}