diff --git a/src/iperf3.1 b/src/iperf3.1

index 05483a9..35a0873 100644

--- a/src/iperf3.1

+++ b/src/iperf3.1

@@ -329,6 +329,13 @@ If the client is run with \fB--json\fR, the server output is included

 in a JSON object; otherwise it is appended at the bottom of the

 human-readable output.

 .TP

+.BR --udp-counters-64bit

+Use 64-bit counters in UDP test packets.

+The use of this option can help prevent counter overflows during long

+or high-bitrate UDP tests.  Both client and server need to be running

+at least version 3.1 for this option to work.  It may become the

+default behavior at some point in the future.

+.TP

 .BR --username " \fIusername\fR" 

 username to use for authentication to the iperf server (if built with

 OpenSSL support).