diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 19329dd103..e3d852cdc7 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -9569,7 +9569,10 @@ CREATE TYPE rainbow AS ENUM ('red', 'orange', 'yellow', 'green', 'blue', 'purple
to_tsvector( config> regconfig> , document> json(b))
tsvector
- reduce document text to tsvector>
+
+ reduce each string value in the document to a tsvector>, and then
+ concatentate those in document order to produce a single tsvector>
+
to_tsvector('english', '{"a": "The Fat Rats"}'::json)
'fat':2 'rat':3