diff --git a/boards/sim/sim/sim/configs/rpproxy/defconfig b/boards/sim/sim/sim/configs/rpproxy/defconfig
index 2d347ebe5d..a1002c2853 100644
--- a/boards/sim/sim/sim/configs/rpproxy/defconfig
+++ b/boards/sim/sim/sim/configs/rpproxy/defconfig
@@ -71,7 +71,7 @@ CONFIG_SENSORS_RPMSG=y
 CONFIG_SIG_DEFAULT=y
 CONFIG_SIM_M32=y
 CONFIG_SYSLOG_PREFIX=y
-CONFIG_SYSLOG_PREFIX_STRING="proxy: "
+CONFIG_SYSLOG_PREFIX_STRING="proxy"
 CONFIG_SYSLOG_RPMSG=y
 CONFIG_SYSLOG_RPMSG_SERVER_NAME="server"
 CONFIG_SYSLOG_TIMESTAMP=y
diff --git a/boards/sim/sim/sim/configs/rpserver/defconfig b/boards/sim/sim/sim/configs/rpserver/defconfig
index fbe68c5a8b..8df08034a0 100644
--- a/boards/sim/sim/sim/configs/rpserver/defconfig
+++ b/boards/sim/sim/sim/configs/rpserver/defconfig
@@ -96,7 +96,7 @@ CONFIG_SIM_RPTUN_MASTER=y
 CONFIG_SIM_UART0_NAME="/dev/ttyUSB0"
 CONFIG_SIM_UART_NUMBER=1
 CONFIG_SYSLOG_PREFIX=y
-CONFIG_SYSLOG_PREFIX_STRING="server: "
+CONFIG_SYSLOG_PREFIX_STRING="server"
 CONFIG_SYSLOG_RPMSG_SERVER=y
 CONFIG_SYSLOG_TIMESTAMP=y
 CONFIG_SYSTEM_CLE=y