diff --git a/integrations/codebase/zulip_codebase_mirror b/integrations/codebase/zulip_codebase_mirror
index c3e7863..847cef6 100755
--- a/integrations/codebase/zulip_codebase_mirror
+++ b/integrations/codebase/zulip_codebase_mirror
@@ -110,7 +110,7 @@ def handle_event(event):
         project_name = raw_props.get('name')
         project_repo_type = raw_props.get('scm_type')
 
-        url = make_url("projects/%s" % project_link)
+        url = make_url("projects/%s" % (project_link,))
         scm = "of type %s" % (project_repo_type,) if project_repo_type else ""