diff --git a/nuttx-configs/px4io-v1/nsh/defconfig b/nuttx-configs/px4io-v1/nsh/defconfig
index 0281a96f00..2fc832daf5 100755
--- a/nuttx-configs/px4io-v1/nsh/defconfig
+++ b/nuttx-configs/px4io-v1/nsh/defconfig
@@ -778,7 +778,7 @@ CONFIG_USART1_SERIAL_CONSOLE=y
 # USART1 Configuration
 #
 CONFIG_USART1_RXBUFSIZE=64
-CONFIG_USART1_TXBUFSIZE=64
+CONFIG_USART1_TXBUFSIZE=40
 CONFIG_USART1_BAUD=115200
 CONFIG_USART1_BITS=8
 CONFIG_USART1_PARITY=0