diff --git a/docs/advanced.md b/docs/advanced.md
index 0bbde7038..11cf26f15 100644
--- a/docs/advanced.md
+++ b/docs/advanced.md
@@ -341,7 +341,7 @@ XO will try to find the right prefix for each IP address. If it can't find a pre
   - Create a token with "Write enabled"
 - Add a UUID custom field:
   - Got to Admin > Custom fields > Add custom field
-  - Create a custom field called "uuid"
+  - Create a custom field called "uuid" (lower case!)
   - Assign it to object types `virtualization > cluster` and `virtualization > virtual machine`
 
 ![](./assets/customfield.png)