diff --git a/completions/iperf b/completions/iperf
index 016881463ac..ef2860a8748 100644
--- a/completions/iperf
+++ b/completions/iperf
@@ -5,16 +5,16 @@ _comp_cmd_iperf()
     local cur prev words cword was_split comp_args
     _comp_initialize -s -n : -- "$@" || return
 
-    local noargopts='!(-*|*[ilpwMXbntLPTZCkOSAfIoFBcxy]*)'
+    local noargopts='!(-*|*[ilpwMXbntLPTZCkOAfIoFBcxy]*)'
     # shellcheck disable=SC2254
     case $prev in
         --help | --version | --interval | --len | --port | --window | --mss | --bandwidth | \
             --num | --time | --listenport | --parallel | --ttl | --linux-congestion | --omit | \
             --congestion | --bytes | --blockcount | --cport | --set-mss | --flowlabel | \
-            --title | --tos | --affinity | --rcv-timeout | --server-bitrate-limit | \
+            --title | --affinity | --rcv-timeout | --server-bitrate-limit | \
             --idle-timeout | --time-skew-threshold | --xbind | --nstreams | --connect-timeout | \
             --bitrate | --pacing-timer | --fq-rate | --length | --dscp | --extra-data | \
-            --username | -${noargopts}[hvilpwMXbntLPTZCkOSA])
+            --username | -${noargopts}[hvilpwMXbntLPTZCkOA])
             return
             ;;
         --format | -${noargopts}f)
@@ -59,6 +59,10 @@ _comp_cmd_iperf()
             _comp_compgen_filedir log
             return
             ;;
+        --tos | -${noargopts}S)
+            _comp_compgen -- -W '{0..255}'
+            return
+            ;;
         --rsa-private-key-path | --rsa-public-key-path)
             _comp_compgen_filedir pem
             return