diff --git a/src/posix/platform/hdlc_interface.cpp b/src/posix/platform/hdlc_interface.cpp
index 932daef6c..07da129b0 100644
--- a/src/posix/platform/hdlc_interface.cpp
+++ b/src/posix/platform/hdlc_interface.cpp
@@ -409,10 +409,8 @@ exit:
 
 int HdlcInterface::OpenFile(const char *aFile, Arguments &aArguments)
 {
-    int         fd       = -1;
-    int         rval     = 0;
-    const char *parity   = aArguments.GetValue("uart-parity");
-    uint32_t    baudrate = 115200;
+    int fd   = -1;
+    int rval = 0;
 
     fd = open(aFile, O_RDWR | O_NOCTTY | O_NONBLOCK | O_CLOEXEC);
     if (fd == -1)
@@ -424,9 +422,11 @@ int HdlcInterface::OpenFile(const char *aFile, Arguments &aArguments)
     if (isatty(fd))
     {
         struct termios tios;
+        const char *   value;
+        speed_t        speed;
 
-        unsigned int speed   = 115200;
-        int          stopBit = 1;
+        int      stopBit  = 1;
+        uint32_t baudrate = 115200;
 
         VerifyOrExit((rval = tcgetattr(fd, &tios)) == 0, OT_NOOP);
 
@@ -434,14 +434,14 @@ int HdlcInterface::OpenFile(const char *aFile, Arguments &aArguments)
 
         tios.c_cflag = CS8 | HUPCL | CREAD | CLOCAL;
 
-        if (parity)
+        if ((value = aArguments.GetValue("uart-parity")) != NULL)
         {
-            if (strncmp(parity, "odd", 3) == 0)
+            if (strncmp(value, "odd", 3) == 0)
             {
                 tios.c_cflag |= PARENB;
                 tios.c_cflag |= PARODD;
             }
-            else if (strncmp(parity, "even", 4) == 0)
+            else if (strncmp(value, "even", 4) == 0)
             {
                 tios.c_cflag |= PARENB;
             }
@@ -451,9 +451,9 @@ int HdlcInterface::OpenFile(const char *aFile, Arguments &aArguments)
             }
         }
 
-        if (aArguments.GetValue("uart-stop"))
+        if ((value = aArguments.GetValue("uart-stop")) != NULL)
         {
-            stopBit = atoi(aArguments.GetValue("uart-stop"));
+            stopBit = atoi(value);
         }
 
         switch (stopBit)
@@ -469,10 +469,11 @@ int HdlcInterface::OpenFile(const char *aFile, Arguments &aArguments)
             break;
         }
 
-        if (aArguments.GetValue("uart-baudrate"))
+        if ((value = aArguments.GetValue("uart-baudrate")))
         {
-            baudrate = static_cast<uint32_t>(atoi(aArguments.GetValue("uart-baudrate")));
+            baudrate = static_cast<uint32_t>(atoi(value));
         }
+
         switch (baudrate)
         {
         case 9600:
@@ -601,7 +602,14 @@ int HdlcInterface::ForkPty(const char *aCommand, const char *aArguments)
         const int kMaxCommand = 255;
         char      cmd[kMaxCommand];
 
-        rval = snprintf(cmd, sizeof(cmd), "exec %s %s", aCommand, aArguments);
+        if (aArguments == NULL)
+        {
+            rval = snprintf(cmd, sizeof(cmd), "exec %s", aCommand);
+        }
+        else
+        {
+            rval = snprintf(cmd, sizeof(cmd), "exec %s %s", aCommand, aArguments);
+        }
         VerifyOrExit(rval > 0 && static_cast<size_t>(rval) < sizeof(cmd),
                      fprintf(stderr, "NCP file and configuration is too long!");
                      rval = -1);
diff --git a/src/posix/platform/radio_url.cpp b/src/posix/platform/radio_url.cpp
index c75892227..ac566525b 100644
--- a/src/posix/platform/radio_url.cpp
+++ b/src/posix/platform/radio_url.cpp
@@ -73,6 +73,7 @@ const char *otSysGetRadioUrlHelpString(void)
     "    uart-parity[=even|odd]         Uart parity config, optional.\n"                             \
     "    uart-stop[=number-of-bits]     Uart stop bit, default is 1.\n"                              \
     "    uart-baudrate[=baudrate]       Uart baud rate, default is 115200.\n"                        \
+    "    uart-flow-control              Enable flow control, disabled by default.\n"                 \
     "    forkpty-arg[=argument string]  Command line arguments for subprocess, can be repeated.\n"
 
 #endif // OPENTHREAD_POSIX_CONFIG_RCP_BUS == OT_POSIX_RCP_BUS_SPI
diff --git a/src/posix/platform/spi_interface.cpp b/src/posix/platform/spi_interface.cpp
index 63265ee11..8e4ea191d 100644
--- a/src/posix/platform/spi_interface.cpp
+++ b/src/posix/platform/spi_interface.cpp
@@ -103,6 +103,7 @@ otError SpiInterface::Init(Arguments &aArguments)
     uint16_t    spiCsDelay         = OT_PLATFORM_CONFIG_SPI_DEFAULT_CS_DELAY_US;
     uint8_t     spiAlignAllowance  = OT_PLATFORM_CONFIG_SPI_DEFAULT_ALIGN_ALLOWANCE;
     uint8_t     spiSmallPacketSize = OT_PLATFORM_CONFIG_SPI_DEFAULT_SMALL_PACKET_SIZE;
+    const char *value;
 
     spiGpioIntDevice   = aArguments.GetValue("gpio-int-device");
     spiGpioResetDevice = aArguments.GetValue("gpio-reset-device");
@@ -111,45 +112,45 @@ otError SpiInterface::Init(Arguments &aArguments)
         DieNow(OT_EXIT_INVALID_ARGUMENTS);
     }
 
-    if (aArguments.GetValue("gpio-int-line"))
+    if ((value = aArguments.GetValue("gpio-int-line")))
     {
-        spiGpioIntLine = static_cast<uint8_t>(atoi(aArguments.GetValue("gpio-int-line")));
+        spiGpioIntLine = static_cast<uint8_t>(atoi(value));
     }
     else
     {
         DieNow(OT_EXIT_INVALID_ARGUMENTS);
     }
-    if (aArguments.GetValue("gpio-reset-line"))
+    if ((value = aArguments.GetValue("gpio-reset-line")))
     {
-        spiGpioResetLine = static_cast<uint8_t>(atoi(aArguments.GetValue("gpio-reset-line")));
+        spiGpioResetLine = static_cast<uint8_t>(atoi(value));
     }
     else
     {
         DieNow(OT_EXIT_INVALID_ARGUMENTS);
     }
-    if (aArguments.GetValue("spi-mode"))
+    if ((value = aArguments.GetValue("spi-mode")))
     {
-        spiMode = static_cast<uint8_t>(atoi(aArguments.GetValue("spi-mode")));
+        spiMode = static_cast<uint8_t>(atoi(value));
     }
-    if (aArguments.GetValue("spi-speed"))
+    if ((value = aArguments.GetValue("spi-speed")))
     {
-        spiSpeed = static_cast<uint32_t>(atoi(aArguments.GetValue("spi-speed")));
+        spiSpeed = static_cast<uint32_t>(atoi(value));
     }
-    if (aArguments.GetValue("spi-reset-delay"))
+    if ((value = aArguments.GetValue("spi-reset-delay")))
     {
-        spiResetDelay = static_cast<uint32_t>(atoi(aArguments.GetValue("spi-reset-delay")));
+        spiResetDelay = static_cast<uint32_t>(atoi(value));
     }
-    if (aArguments.GetValue("spi-cs-delay"))
+    if ((value = aArguments.GetValue("spi-cs-delay")))
     {
-        spiCsDelay = static_cast<uint16_t>(atoi(aArguments.GetValue("spi-cs-delay")));
+        spiCsDelay = static_cast<uint16_t>(atoi(value));
     }
-    if (aArguments.GetValue("spi-align-allowance"))
+    if ((value = aArguments.GetValue("spi-align-allowance")))
     {
-        spiAlignAllowance = static_cast<uint8_t>(atoi(aArguments.GetValue("spi-align-allowance")));
+        spiAlignAllowance = static_cast<uint8_t>(atoi(value));
     }
-    if (aArguments.GetValue("spi-small-packet"))
+    if ((value = aArguments.GetValue("spi-small-packet")))
     {
-        spiSmallPacketSize = static_cast<uint8_t>(atoi(aArguments.GetValue("spi-small-packet")));
+        spiSmallPacketSize = static_cast<uint8_t>(atoi(value));
     }
 
     VerifyOrDie(spiAlignAllowance <= kSpiAlignAllowanceMax, OT_EXIT_FAILURE);