diff --git a/bookwyrm/utils/validate.py b/bookwyrm/utils/validate.py
index a6272319b..89aee4782 100644
--- a/bookwyrm/utils/validate.py
+++ b/bookwyrm/utils/validate.py
@@ -4,7 +4,10 @@ from bookwyrm.settings import DOMAIN, USE_HTTPS
 
 def validate_url_domain(url, default="/"):
     """Basic check that the URL starts with the instance domain name"""
-    if url in ("/", default, None):
+    if not url:
+        return default
+
+    if url in ("/", default):
         return url
 
     protocol = "https://" if USE_HTTPS else "http://"