diff --git a/configs/nutiny-nuc120/nsh/defconfig b/configs/nutiny-nuc120/nsh/defconfig
index 72d120bfccb..d884480f2fb 100644
--- a/configs/nutiny-nuc120/nsh/defconfig
+++ b/configs/nutiny-nuc120/nsh/defconfig
@@ -327,8 +327,8 @@ CONFIG_UART1_SERIAL_CONSOLE=y
 #
 # UART1 Configuration
 #
-CONFIG_UART1_RXBUFSIZE=256
-CONFIG_UART1_TXBUFSIZE=256
+CONFIG_UART1_RXBUFSIZE=64
+CONFIG_UART1_TXBUFSIZE=64
 CONFIG_UART1_BAUD=115200
 CONFIG_UART1_BITS=8
 CONFIG_UART1_PARITY=0
@@ -562,7 +562,7 @@ CONFIG_NSH_DISABLE_UMOUNT=y
 CONFIG_NSH_DISABLE_WGET=y
 # CONFIG_NSH_DISABLE_XD is not set
 CONFIG_NSH_CODECS_BUFSIZE=128
-CONFIG_NSH_FILEIOSIZE=512
+CONFIG_NSH_FILEIOSIZE=64
 CONFIG_NSH_LINELEN=80
 CONFIG_NSH_NESTDEPTH=3
 CONFIG_NSH_DISABLESCRIPT=y
diff --git a/configs/xtrs/src/xtr_serial.c b/configs/xtrs/src/xtr_serial.c
index eb6846179a6..c56aa8403d7 100644
--- a/configs/xtrs/src/xtr_serial.c
+++ b/configs/xtrs/src/xtr_serial.c
@@ -122,7 +122,7 @@ static bool up_txempty(FAR struct uart_dev_s *dev);
  * Private Variables
  ****************************************************************************/
 
-struct uart_ops_s g_uart_ops =
+static const struct uart_ops_s g_uart_ops =
 {
   up_setup,                 /* setup */
   up_shutdown,              /* shutdown */
diff --git a/configs/z80sim/src/z80_serial.c b/configs/z80sim/src/z80_serial.c
index 27d68509349..e06ac96e72a 100644
--- a/configs/z80sim/src/z80_serial.c
+++ b/configs/z80sim/src/z80_serial.c
@@ -87,7 +87,7 @@ static bool up_txempty(FAR struct uart_dev_s *dev);
  * Private Variables
  ****************************************************************************/
 
-struct uart_ops_s g_uart_ops =
+static const struct uart_ops_s g_uart_ops =
 {
   up_setup,                 /* setup */
   up_shutdown,              /* shutdown */