diff --git a/docs/cmdline-opts/write-out.d b/docs/cmdline-opts/write-out.d
index b2ac2ec060..e069afcf1e 100644
--- a/docs/cmdline-opts/write-out.d
+++ b/docs/cmdline-opts/write-out.d
@@ -91,7 +91,7 @@ curl CONNECT request. (Added in 7.12.4)
 The http version that was effectively used. (Added in 7.50.0)
 .TP
 **json**
-A JSON object with all available keys.
+A JSON object with all available keys. (Added in 7.70.0)
 .TP
 **local_ip**
 The IP address of the local end of the most recently done connection - can be