diff --git a/make_data_uris.py b/make_data_uris.py
index cd90bf60..84803f83 100644
--- a/make_data_uris.py
+++ b/make_data_uris.py
@@ -20,6 +20,6 @@ for filename in os.listdir('img/'):
         continue
     filecontent = open('img/' + filename).read()
     b64 = base64.encodestring(filecontent).replace('\n', '')
-    data_uris.append('$data_uri_%(varname)s: "data:%(mimetype)s;base64,%(b64)s";' % locals())
+    data_uris.append('$data_uri_%(varname)s: "data:%(mimetype)s;base64,%(b64)s" !default;' % locals())
 
 open('_data_uris.scss', 'w').write('\n'.join(data_uris))