diff --git a/CONTRIBUTE b/CONTRIBUTE
index ed42c4b8116..9bbadb0135d 100644
--- a/CONTRIBUTE
+++ b/CONTRIBUTE
@@ -136,7 +136,7 @@ command to index them; for instance, use @vindex for variables and
 https://www.gnu.org/software/texinfo/manual/texinfo/html_node/Predefined-Indices.html
 or run the shell command 'info "(texinfo)Predefined Indices"'.
 
-We prefer American English both in doc strings and in the manuals.
+We prefer American English in doc strings, manuals, messages, and identifiers.
 That includes both spelling (e.g., "behavior", not "behaviour") and
 the convention of leaving 2 spaces between sentences.