diff --git a/src/php-8.1-strftime.php b/src/php-8.1-strftime.php
index 4f8f916..076538e 100644
--- a/src/php-8.1-strftime.php
+++ b/src/php-8.1-strftime.php
@@ -8,6 +8,7 @@
   use IntlDateFormatter;
   use IntlGregorianCalendar;
   use InvalidArgumentException;
+  use Locale;
 
   /**
    * Locale-formatted strftime using IntlDateFormatter (PHP 8.1 compatible)
@@ -40,12 +41,7 @@ function strftime (string $format, $timestamp = null, ?string $locale = null) :
 
     $timestamp->setTimezone(new DateTimeZone(date_default_timezone_get()));
 
-    if (empty($locale)) {
-      // get current locale
-      $locale = setlocale(LC_TIME, '0');
-    }
-    // remove trailing part not supported by ext-intl locale
-    $locale = preg_replace('/[^\w-].*$/', '', $locale);
+    $locale = Locale::canonicalize($locale ?? setlocale(LC_TIME, '0'));
 
     $intl_formats = [
       '%a' => 'EEE',	// An abbreviated textual representation of the day	Sun through Sat