diff --git a/script/check-posix-pty b/script/check-posix-pty
index 94aa1782e..8cfcc6b54 100755
--- a/script/check-posix-pty
+++ b/script/check-posix-pty
@@ -124,6 +124,9 @@ do_check()
         OT_CTL="$PWD/build/posix/src/posix/ot-ctl"
         sudo "${OT_CTL}" -I "${NETIF_NAME}" panid 0xface | grep 'Done' || die 'failed to set panid with ot-ctl'
 
+        # verify supports options in OpenThread commands without separator --
+        sudo "${OT_CTL}" -I "${NETIF_NAME}" pskc -p 123456 | grep 'Done' || die 'unable to set pskc'
+
         # verify this reset and factoryreset end immediately
         sudo "${OT_CTL}" -I "${NETIF_NAME}" reset
         # sleep a while for daemon ready
diff --git a/src/posix/client.cpp b/src/posix/client.cpp
index a80a5f4b4..2a3940fdf 100644
--- a/src/posix/client.cpp
+++ b/src/posix/client.cpp
@@ -208,7 +208,7 @@ Config ParseArg(int &aArgCount, char **&aArgVector)
 
     optind = 1;
 
-    for (int index, option; (option = getopt_long(aArgCount, aArgVector, "I:h", kOptions, &index)) != -1;)
+    for (int index, option; (option = getopt_long(aArgCount, aArgVector, "+I:h", kOptions, &index)) != -1;)
     {
         switch (option)
         {