diff --git a/homeassistant/components/frontend/__init__.py b/homeassistant/components/frontend/__init__.py
index 942022553ad..3e596381321 100644
--- a/homeassistant/components/frontend/__init__.py
+++ b/homeassistant/components/frontend/__init__.py
@@ -1,6 +1,7 @@
 """Handle the frontend for Home Assistant."""
 import json
 import logging
+import mimetypes
 import os
 import pathlib
 
@@ -20,6 +21,13 @@ from homeassistant.loader import bind_hass
 
 from .storage import async_setup_frontend_storage
 
+
+# Fix mimetypes for borked Windows machines
+# https://github.com/home-assistant/home-assistant-polymer/issues/3336
+mimetypes.add_type("text/css", ".css")
+mimetypes.add_type("application/javascript", ".js")
+
+
 DOMAIN = 'frontend'
 CONF_THEMES = 'themes'
 CONF_EXTRA_HTML_URL = 'extra_html_url'