diff --git a/src/wp-includes/functions.php b/src/wp-includes/functions.php
index 536f195b14..3e1866330c 100644
--- a/src/wp-includes/functions.php
+++ b/src/wp-includes/functions.php
@@ -3142,7 +3142,7 @@ function wp_get_mime_types() {
 			'class'                        => 'application/java',
 			'tar'                          => 'application/x-tar',
 			'zip'                          => 'application/zip',
-			'gz|gzip'                      => 'application/x-gzip',
+			'gz|gzip|tgz'                  => 'application/gzip',
 			'rar'                          => 'application/rar',
 			'7z'                           => 'application/x-7z-compressed',
 			'exe'                          => 'application/x-msdownload',
diff --git a/tests/phpunit/tests/formatting/SanitizeMimeType.php b/tests/phpunit/tests/formatting/SanitizeMimeType.php
index 45c8ec611f..5d58742c7e 100644
--- a/tests/phpunit/tests/formatting/SanitizeMimeType.php
+++ b/tests/phpunit/tests/formatting/SanitizeMimeType.php
@@ -25,7 +25,7 @@ class Tests_Formatting_SanitizeMimeType extends WP_UnitTestCase {
 			'application/xml-dtd',
 			'application/xop+xml',
 			'application/zip',
-			'application/x-gzip',
+			'application/gzip',
 			'audio/basic',
 			'image/jpeg',
 			'text/css',