diff --git a/build/controllers/MimeTypeController.php b/build/controllers/MimeTypeController.php
index 2724451f04..2822fb6c11 100644
--- a/build/controllers/MimeTypeController.php
+++ b/build/controllers/MimeTypeController.php
@@ -33,6 +33,13 @@ class MimeTypeController extends Controller
         'text/xml' => 'application/xml',
     ];
 
+    /**
+     * @var array MIME types to add to the ones parsed from Apache files
+     */
+    private $additionalMimeTypes = [
+        'mjs' => 'text/javascript',
+    ];
+
     /**
      * @param string $outFile the mime file to update. Defaults to @yii/helpers/mimeTypes.php
      * @param string $aliasesOutFile the aliases file to update. Defaults to @yii/helpers/mimeAliases.php
@@ -47,9 +54,9 @@ class MimeTypeController extends Controller
             $aliasesOutFile = Yii::getAlias('@yii/helpers/mimeAliases.php');
         }
 
-        $this->stdout('downloading mime-type file from apache httpd repository...');
+        $this->stdout('Downloading mime-type file from apache httpd repository...');
         if ($apacheMimeTypesFileContent = file_get_contents('http://svn.apache.org/viewvc/httpd/httpd/trunk/docs/conf/mime.types?view=co')) {
-            $this->stdout("done.\n", Console::FG_GREEN);
+            $this->stdout("Done.\n", Console::FG_GREEN);
             $this->generateMimeTypesFile($outFile, $apacheMimeTypesFileContent);
             $this->generateMimeAliasesFile($aliasesOutFile);
         } else {
@@ -63,7 +70,7 @@ class MimeTypeController extends Controller
      */
     private function generateMimeTypesFile($outFile, $content)
     {
-        $this->stdout("generating file $outFile...");
+        $this->stdout("Generating file $outFile...");
         $mimeMap = [];
         foreach (explode("\n", $content) as $line) {
             $line = trim($line);
@@ -78,6 +85,7 @@ class MimeTypeController extends Controller
                 }
             }
         }
+        $mimeMap = array_merge($mimeMap, $this->additionalMimeTypes);
         ksort($mimeMap);
         $array = VarDumper::export($mimeMap);
         $content = <<<EOD
diff --git a/framework/CHANGELOG.md b/framework/CHANGELOG.md
index a40fd65405..6c1aa84447 100644
--- a/framework/CHANGELOG.md
+++ b/framework/CHANGELOG.md
@@ -5,7 +5,7 @@ Yii Framework 2 Change Log
 ------------------------
 
 - Bug #12077, #12135, #17263: Fixed PostgreSQL version of `alterColumn()` to accept properly `ColumnSchemaBuilder` definition of column (bizley)
-
+- Bug #17306: Added ".mjs" extensions to mimetypes meta (samdark)
 
 2.0.18 April 23, 2019
 ---------------------
diff --git a/framework/helpers/mimeTypes.php b/framework/helpers/mimeTypes.php
index b6fab4f72d..9571307915 100644
--- a/framework/helpers/mimeTypes.php
+++ b/framework/helpers/mimeTypes.php
@@ -448,6 +448,7 @@ return [
     'mime' => 'message/rfc822',
     'mj2' => 'video/mj2',
     'mjp2' => 'video/mj2',
+    'mjs' => 'text/javascript',
     'mk3d' => 'video/x-matroska',
     'mka' => 'audio/x-matroska',
     'mks' => 'video/x-matroska',
@@ -479,6 +480,7 @@ return [
     'mpkg' => 'application/vnd.apple.installer+xml',
     'mpm' => 'application/vnd.blueice.multipass',
     'mpn' => 'application/vnd.mophun.application',
+    0 => 'application/vnd.lotus-1-2-3',
     'mpp' => 'application/vnd.ms-project',
     'mpt' => 'application/vnd.ms-project',
     'mpy' => 'application/vnd.ibm.minipay',
@@ -991,5 +993,4 @@ return [
     'zir' => 'application/vnd.zul',
     'zirz' => 'application/vnd.zul',
     'zmm' => 'application/vnd.handheld-entertainment+xml',
-    123 => 'application/vnd.lotus-1-2-3',
 ];