diff --git a/src/iperf3.1 b/src/iperf3.1
index 639d5a4..1be8cc3 100644
--- a/src/iperf3.1
+++ b/src/iperf3.1
@@ -350,6 +350,13 @@ 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).