diff --git a/src/iperf.h b/src/iperf.h
index 9278c3d..225cd1a 100644
--- a/src/iperf.h
+++ b/src/iperf.h
@@ -191,7 +191,7 @@ struct iperf_test
 #define uS_TO_NS 1000
 #define SEC_TO_US 1000000LL
 #define RATE (1024 * 1024) /* 1 Mbps */
-#define DURATION 5 /* seconds */
+#define DURATION 10 /* seconds */
 
 #define SEC_TO_NS 1000000000LL	/* too big for enum/const on some platforms */
 #define MAX_RESULT_STRING 4096
diff --git a/src/iperf3.1 b/src/iperf3.1
index 27c8894..13807c8 100644
--- a/src/iperf3.1
+++ b/src/iperf3.1
@@ -71,7 +71,7 @@ time in seconds to transmit for (default 10 secs)
 number of bytes to transmit (instead of -t)
 .TP
 .BR -l ", " --length " \fIn\fR[KM]"
-set length read/write buffer to \fIn\fR (default 128 KB)
+length of buffer to read or write (default 128 KB for TCP, 8KB for UDP)
 .TP
 .BR -P ", " --parallel " \fIn\fR"
 number of parallel client streams to run
diff --git a/src/iperf_api.c b/src/iperf_api.c
index f090acd..f2e041e 100644
--- a/src/iperf_api.c
+++ b/src/iperf_api.c
@@ -67,7 +67,7 @@ usage()
 void
 usage_long()
 {
-    fputs(usage_longstr, stderr);
+    fprintf(stderr, usage_longstr, RATE / (1024*1024), DURATION, DEFAULT_TCP_BLKSIZE / 1024, DEFAULT_UDP_BLKSIZE / 1024);
 }
 
 
diff --git a/src/locale.c b/src/locale.c
index 3c76b9a..39617af 100644
--- a/src/locale.c
+++ b/src/locale.c
@@ -83,11 +83,12 @@ const char usage_longstr[] = "Usage: iperf [-s|-c host] [options]\n"
                            "  -c, --client    <host>    run in client mode, connecting to <host>\n"
                            "  -u, --udp                 use UDP rather than TCP\n"
                            "  -b, --bandwidth #[KMG]    for UDP, bandwidth to send at in bits/sec\n"
-                           "                            (default 1 Mbit/sec, implies -u)\n"
-                           "  -t, --time      #         time in seconds to transmit for (default 10 secs)\n"
+                           "                            (default %d Mbit/sec)\n"
+                           "  -t, --time      #         time in seconds to transmit for (default %d secs)\n"
                            "  -n, --num       #[KMG]    number of bytes to transmit (instead of -t)\n"
-                           "  -l, --len       #[KMG]    length of buffer to read or write (default 8 KB)\n"
-                           "  -P, --parallel  #         number of parallel client threads to run\n"
+                           "  -l, --len       #[KMG]    length of buffer to read or write\n"
+			   "                            (default %d KB for TCP, %d KB for UDP)\n"
+                           "  -P, --parallel  #         number of parallel client streams to run\n"
                            "  -R, --reverse             run in reverse mode (server sends, client receives)\n"
                            "  -w, --window    #[KMG]    TCP window size (socket buffer size)\n"
                            "  -B, --bind      <host>    bind to a specific interface or multicast address\n"