diff --git a/doc/manual/expressions/builtins.xml b/doc/manual/expressions/builtins.xml
index 6ac802343..9517f2010 100644
--- a/doc/manual/expressions/builtins.xml
+++ b/doc/manual/expressions/builtins.xml
@@ -995,9 +995,9 @@ in foo
Convert the expression
e to a string.
e can be a string (in which case
- toString is a no-op) or a path (e.g.,
+ toString is a no-op), a path (e.g.,
toString /foo/bar yields
- "/foo/bar".
+ "/foo/bar" or a set containing { __toString = self: ...; }.