diff --git a/luci-app-iperf/luasrc/controller/iperf.lua b/luci-app-iperf/luasrc/controller/iperf.lua
index 434851278..33a1e8daa 100644
--- a/luci-app-iperf/luasrc/controller/iperf.lua
+++ b/luci-app-iperf/luasrc/controller/iperf.lua
@@ -33,9 +33,9 @@ function run_test(server,proto,mode,updown,omit,parallel,transmit,bitrate)
 		end
 	else
 		if updown == "upload" then
-			iperf = io.popen("iperf3 -c %s -P %s -%s -p %s -O %s -t %s -u -b %s -J" % {ut.shellquote(addr),parallel,ipv,port,omit,transmit,bitrate})
+			iperf = io.popen("iperf3 -c %s -P %s -%s -p %s -O %s -t %s -u -b %sm -J" % {ut.shellquote(addr),parallel,ipv,port,omit,transmit,bitrate})
 		else
-			iperf = io.popen("iperf3 -c %s -P %s -%s -p %s -O %s -R -t %s -u -b %s -J" % {ut.shellquote(addr),parallel,ipv,port,omit,transmit,bitrate})
+			iperf = io.popen("iperf3 -c %s -P %s -%s -p %s -O %s -R -t %s -u -b %sm -J" % {ut.shellquote(addr),parallel,ipv,port,omit,transmit,bitrate})
 		end
 	end
 	if iperf then