diff --git a/UI/WebServerResources/UIxContactEditor.js b/UI/WebServerResources/UIxContactEditor.js
index 074d1090a..13fe0a444 100644
--- a/UI/WebServerResources/UIxContactEditor.js
+++ b/UI/WebServerResources/UIxContactEditor.js
@@ -161,7 +161,7 @@ function saveCategories() {
                 newCategories.push(newValue);
             }
         }
-        var json = newCategories.toJSON();
+        var json = Object.toJSON(newCategories);
         catsInput.value = json;
     }
 }