diff --git a/src/iperf_locale.c b/src/iperf_locale.c
index 32883da84..470a5cc7a 100644
--- a/src/iperf_locale.c
+++ b/src/iperf_locale.c
@@ -170,8 +170,10 @@ const char usage_longstr[] = "Usage: iperf3 [-s|-c host] [options]\n"
 			   "                            bits/sec (Linux only)\n"
 #endif
                            "  -t, --time      #         time in seconds to transmit for (default %d secs)\n"
-                           "  -n, --bytes     #[KMG]    number of bytes to transmit (instead of -t)\n"
-                           "  -k, --blockcount #[KMG]   number of blocks (packets) to transmit (instead of -t or -n)\n"
+                           "  -n, --bytes     #[KMG]    transmit until the end of the interval when the client sent or received\n"
+                           "                            (per direction) at least this number of bytes (instead of -t or -k)\n"
+                           "  -k, --blockcount #[KMG]   transmit until the end of the interval when the client sent or received\n"
+                           "                            (per direction) at least this number of blocks (instead of -t or -n)\n"
                            "  -l, --length    #[KMG]    length of buffer to read or write\n"
 			   "                            (default %d KB for TCP, dynamic or %d for UDP)\n"
                            "  --cport         <port>    bind to a specific client port (TCP and UDP, default: ephemeral port)\n"