diff --git a/build.py b/build.py
index 6054f05..05f7dc0 100644
--- a/build.py
+++ b/build.py
@@ -3,7 +3,7 @@ import logging
 import os
 
 def wrap_url(u):
-    if u.startswith("http"):
+    if u == '' or u.startswith("http"):
         return u
     return f'http://{u}'