diff --git a/framework/CHANGELOG.md b/framework/CHANGELOG.md
index 93f092d..ddf4b51 100644
--- a/framework/CHANGELOG.md
+++ b/framework/CHANGELOG.md
@@ -4,7 +4,7 @@ Yii Framework 2 Change Log
 2.0.45 under development
 ------------------------
 
-- no changes in this release.
+- Bug #19138: Allow digits in language code (ntesic)
 
 
 2.0.44 December 30, 2021
diff --git a/framework/i18n/GettextMessageSource.php b/framework/i18n/GettextMessageSource.php
index b3190ba..2f68f15 100644
--- a/framework/i18n/GettextMessageSource.php
+++ b/framework/i18n/GettextMessageSource.php
@@ -131,7 +131,7 @@ class GettextMessageSource extends MessageSource
     protected function getMessageFilePath($language)
     {
         $language = (string) $language;
-        if ($language !== '' && !preg_match('/^[a-z_-]+$/i', $language)) {
+        if ($language !== '' && !preg_match('/^[a-z0-9_-]+$/i', $language)) {
             throw new InvalidArgumentException(sprintf('Invalid language code: "%s".', $language));
         }
         $messageFile = Yii::getAlias($this->basePath) . '/' . $language . '/' . $this->catalog;
diff --git a/framework/i18n/PhpMessageSource.php b/framework/i18n/PhpMessageSource.php
index 4dd860a..dc9f2cf 100644
--- a/framework/i18n/PhpMessageSource.php
+++ b/framework/i18n/PhpMessageSource.php
@@ -134,7 +134,7 @@ class PhpMessageSource extends MessageSource
     protected function getMessageFilePath($category, $language)
     {
         $language = (string) $language;
-        if ($language !== '' && !preg_match('/^[a-z_-]+$/i', $language)) {
+        if ($language !== '' && !preg_match('/^[a-z0-9_-]+$/i', $language)) {
             throw new InvalidArgumentException(sprintf('Invalid language code: "%s".', $language));
         }
         $messageFile = Yii::getAlias($this->basePath) . "/$language/";
diff --git a/tests/data/i18n/messages/en-150/test.php b/tests/data/i18n/messages/en-150/test.php
new file mode 100644
index 0000000..f915300
--- /dev/null
+++ b/tests/data/i18n/messages/en-150/test.php
@@ -0,0 +1,14 @@
+<?php
+/**
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright (c) 2008 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+/**
+ * Messages are copy-pasted in \yiiunit\framework\i18n\DbMessageSourceTest::setUpBeforeClass()
+ * Do not forget to update it in after changing this file!
+ */
+return [
+    'The dog runs fast.' => 'The dog runs fast (en-150).',
+];
diff --git a/tests/framework/i18n/I18NTest.php b/tests/framework/i18n/I18NTest.php
index 727dcbb..5b8ab6a 100644
--- a/tests/framework/i18n/I18NTest.php
+++ b/tests/framework/i18n/I18NTest.php
@@ -129,6 +129,8 @@ class I18NTest extends TestCase
         // target is a different language than source
         $this->assertEquals('Собака бегает быстро.', $i18n->translate('test', $msg, [], 'ru-RU'));
         $this->assertEquals('Собака бегает быстро.', $i18n->translate('test', $msg, [], 'ru'));
+        $this->assertEquals('The dog runs fast (en-150).', $i18n->translate('test', $msg, [], 'en-150'));
+        $this->assertEquals('The dog runs fast.', $i18n->translate('test', $msg, [], 'en'));
 
         // language is set to null
         $this->assertEquals($msg, $i18n->translate('test', $msg, [], null));