diff --git a/static/js/identifyDialog.js b/static/js/identifyDialog.js
index 0745e3e..99c5fee 100644
--- a/static/js/identifyDialog.js
+++ b/static/js/identifyDialog.js
@@ -60,7 +60,7 @@ oml.ui.identifyDialog = function(data) {
                 }),
             isbn: Ox.Input({
                     style: 'squared',
-                    value: Ox.formatISBN(data.isbn, 13, true),
+                    value: Ox.formatISBN(data.isbn || '', 13, true),
                     width: 544
                 })
                 .bindEvent({