diff --git a/setup/plugins_mirror.py b/setup/plugins_mirror.py
index 1a8318231d..1f1b69f458 100644
--- a/setup/plugins_mirror.py
+++ b/setup/plugins_mirror.py
@@ -291,6 +291,8 @@ def fetch_plugin(old_index, entry):
     lm_map = {plugin['thread_id']:plugin for plugin in old_index.itervalues()}
     raw = read(entry.url)
     url, name = parse_plugin_zip_url(raw)
+    if url is None:
+        raise ValueError('Failed to find zip file URL for entry: %s' % repr(entry), file=sys.stderr)
     plugin = lm_map.get(entry.thread_id, None)
 
     if plugin is not None: