diff --git a/config/customMimeTypes.php b/config/customMimeTypes.php
index e3ec006b8..f5c17aa8c 100644
--- a/config/customMimeTypes.php
+++ b/config/customMimeTypes.php
@@ -84,7 +84,7 @@ return [
     'crl' => 'application/pkix-crl',
     'crt' => 'application/x-x509-user-cert',
     'csh' => 'text/x-script.csh',
-    'css' => 'text/css',
+    'css' => ['text/css', 'text/plain'],
     'cst' => 'application/x-director',
     'cxt' => 'application/x-director',
     'cxx' => ['text/x-c', 'text/plain'],
@@ -220,7 +220,7 @@ return [
     'jpgm' => 'video/jpm',
     'jpm' => 'video/jpm',
     'jps' => 'image/x-jps',
-    'js' => 'text/ecmascript',
+    'js' => ['text/ecmascript', 'text/plain'],
     'json' => ['text/plain', 'text/json', 'text/javascript'],
     'jsonp' => 'application/javascript',
     'jut' => 'image/jutvision',