diff --git a/doc/development/i18n/externalization.md b/doc/development/i18n/externalization.md
index 9fb8ea542d9..ce310672dad 100644
--- a/doc/development/i18n/externalization.md
+++ b/doc/development/i18n/externalization.md
@@ -77,6 +77,9 @@ Or:
 hello = _("Hello world!")
 ```
 
+NOTE: **Note:** Messages in the API (`lib/api/` or `app/graphql`) do
+not need to be externalised.
+
 ### HAML files
 
 Given the following content in HAML: