diff --git a/docs/libcurl/opts/CURLOPT_HAPROXYPROTOCOL.md b/docs/libcurl/opts/CURLOPT_HAPROXYPROTOCOL.md
index 77ef0e06f3..1cfb53de60 100644
--- a/docs/libcurl/opts/CURLOPT_HAPROXYPROTOCOL.md
+++ b/docs/libcurl/opts/CURLOPT_HAPROXYPROTOCOL.md
@@ -33,6 +33,10 @@ send this header.
 This option is primarily useful when sending test requests to a service that
 expects this header.
 
+Note that the HAProxy protocol message is only is sent over a freshly setup
+connection. A subsequent transfer that reuses a previous connection does not
+send it again.
+
 Most applications do not need this option.
 
 # DEFAULT