diff --git a/oml/user/models.py b/oml/user/models.py
index ddc3b14..c58e96c 100644
--- a/oml/user/models.py
+++ b/oml/user/models.py
@@ -373,8 +373,8 @@ class Metadata(db.Model):
         if 'isbn' in data and isinstance(data['isbn'], list):
             isbns = [utils.to_isbn13(isbn) for isbn in data['isbn']]
             isbns = [isbn for isbn in isbns if isbn]
-            if isbn:
-                data['isbn'] = isbn
+            if isbns:
+                data['isbn'] = isbns[0]
             else:
                 del data['isbn']
         for key in data: