diff --git a/conf/boards/px4fmu_2.4.makefile b/conf/boards/px4fmu_2.4.makefile
index e1452f66f5..1a0496230c 100644
--- a/conf/boards/px4fmu_2.4.makefile
+++ b/conf/boards/px4fmu_2.4.makefile
@@ -24,7 +24,7 @@ HARD_FLOAT=yes
 FLASH_MODE ?= PX4_BOOTLOADER
 PX4_PROTOTYPE ?= "${PAPARAZZI_HOME}/sw/tools/px4/px4fmu-v2.prototype"
 PX4_BL_PORT ?= "/dev/serial/by-id/usb-3D_Robotics*,/dev/serial/by-id/pci-3D_Robotics*"
-$(TARGET).MAKEFILE = stm32
+
 
 #
 # default LED configuration
diff --git a/conf/boards/px4io_2.4.makefile b/conf/boards/px4io_2.4.makefile
index 42406c6d1d..d6957c71c2 100644
--- a/conf/boards/px4io_2.4.makefile
+++ b/conf/boards/px4io_2.4.makefile
@@ -20,7 +20,7 @@ PX4_BL_PORT ?= "/dev/serial/by-id/usb-FTDI_*"
 PX4_PROTOTYPE ?= "${PAPARAZZI_HOME}/sw/tools/px4/px4io-v2.prototype"
 
 FLASH_MODE ?= PX4_BOOTLOADER
-$(TARGET).MAKEFILE = stm32
+
 
 #
 # default LED configuration
diff --git a/conf/firmwares/subsystems/fixedwing/intermcu_uart.makefile b/conf/firmwares/subsystems/fixedwing/intermcu_uart.makefile
index 2c220b3971..37548b465c 100644
--- a/conf/firmwares/subsystems/fixedwing/intermcu_uart.makefile
+++ b/conf/firmwares/subsystems/fixedwing/intermcu_uart.makefile
@@ -7,15 +7,22 @@ ifeq (,$(findstring $(SEPARATE_FBW),1 TRUE))
 $(error Using intermcu via UART, so dual mcu with separate fbw. Please add <configure name="SEPARATE_FBW" value="1"/>)
 endif
 
+FBW_MODE_LED ?= none
+INTERMCU_BAUD ?= B57600
+
 ifeq ($(TARGET),fbw)
   INTERMCU_PORT ?= UART2
   INTERMCU_PORT_LOWER = $(shell echo $(INTERMCU_PORT) | tr A-Z a-z)
-  fbw.CFLAGS += -DINTERMCU_LINK=$(INTERMCU_PORT_LOWER) -DUSE_$(INTERMCU_PORT) -D$(INTERMCU_PORT)_BAUD=B57600
+  INTERMCU_PORT_UPPER = $(shell echo $(INTERMCU_PORT) | tr a-z A-Z)
+  fbw.CFLAGS += -DINTERMCU_LINK=$(INTERMCU_PORT_LOWER) -DUSE_$(INTERMCU_PORT_UPPER) -D$(INTERMCU_PORT_UPPER)_BAUD=$(INTERMCU_BAUD)
+ifneq ($(FBW_MODE_LED),none)
   fbw.CFLAGS += -DFBW_MODE_LED=$(FBW_MODE_LED)
+endif
 else
   INTERMCU_PORT ?= UART5
   INTERMCU_PORT_LOWER = $(shell echo $(INTERMCU_PORT) | tr A-Z a-z)
-  ap.CFLAGS += -DINTERMCU_LINK=$(INTERMCU_PORT_LOWER) -DUSE_$(INTERMCU_PORT) -D$(INTERMCU_PORT)_BAUD=B57600
+  INTERMCU_PORT_UPPER = $(shell echo $(INTERMCU_PORT) | tr a-z A-Z)
+  ap.CFLAGS += -DINTERMCU_LINK=$(INTERMCU_PORT_LOWER) -DUSE_$(INTERMCU_PORT_UPPER) -D$(INTERMCU_PORT_UPPER)_BAUD=$(INTERMCU_BAUD)
 endif
 
 ifneq ($(TARGET),sim)
diff --git a/conf/firmwares/subsystems/rotorcraft/intermcu_uart.makefile b/conf/firmwares/subsystems/rotorcraft/intermcu_uart.makefile
index 8b2feea188..91b73b7ba3 100644
--- a/conf/firmwares/subsystems/rotorcraft/intermcu_uart.makefile
+++ b/conf/firmwares/subsystems/rotorcraft/intermcu_uart.makefile
@@ -2,28 +2,32 @@
 
 # InterMCU type UART
 
+FBW_MODE_LED ?= none
+INTERMCU_PORT ?= UART3
+INTERMCU_BAUD ?= B230400
+
+INTERMCU_PORT_LOWER = $(shell echo $(INTERMCU_PORT) | tr A-Z a-z)
+INTERMCU_PORT_UPPER = $(shell echo $(INTERMCU_PORT) | tr a-z A-Z)
+
 ifeq ($(TARGET),fbw)
-  INTERMCU_PORT ?= UART3
-  INTERMCU_BAUD ?= B230400
-  INTERMCU_PORT_LOWER = $(shell echo $(INTERMCU_PORT) | tr A-Z a-z)
-  fbw.CFLAGS += -DINTERMCU_LINK=$(INTERMCU_PORT_LOWER) -DUSE_$(INTERMCU_PORT)  -D$(INTERMCU_PORT)_BAUD=$(INTERMCU_BAUD)
+  fbw.CFLAGS += -DINTERMCU_LINK=$(INTERMCU_PORT_LOWER)
+  fbw.CFLAGS += -DUSE_$(INTERMCU_PORT_UPPER) -D$(INTERMCU_PORT_UPPER)_BAUD=$(INTERMCU_BAUD)
   fbw.CFLAGS += -DINTER_MCU_FBW -DDOWNLINK
+ifneq ($(FBW_MODE_LED),none)
   fbw.CFLAGS += -DFBW_MODE_LED=$(FBW_MODE_LED)
+endif
   fbw.srcs += pprzlink/src/pprz_transport.c
   fbw.srcs += subsystems/intermcu/intermcu_fbw.c
 else
-  INTERMCU_PORT ?= UART3
-  INTERMCU_BAUD ?= B230400
-  INTERMCU_PORT_LOWER = $(shell echo $(INTERMCU_PORT) | tr A-Z a-z)
   ap.CFLAGS += -DINTER_MCU_AP -DINTERMCU_LINK=$(INTERMCU_PORT_LOWER)
-  ap.CFLAGS += -DUSE_$(INTERMCU_PORT) -D$(INTERMCU_PORT)_BAUD=$(INTERMCU_BAUD)
+  ap.CFLAGS += -DUSE_$(INTERMCU_PORT_UPPER) -D$(INTERMCU_PORT_UPPER)_BAUD=$(INTERMCU_BAUD)
   $(TARGET).CFLAGS += -DRADIO_CONTROL_TYPE_H=\"subsystems/intermcu/intermcu_ap.h\" -DRADIO_CONTROL
   RADIO_CONTROL_LED ?= none
 ifneq ($(RADIO_CONTROL_LED),none)
     $(TARGET).CFLAGS += -DRADIO_CONTROL_LED=$(RADIO_CONTROL_LED)
 endif
 
-	ap.srcs += subsystems/intermcu/intermcu_ap.c
-	ap.srcs += pprzlink/src/pprz_transport.c
-	$(TARGET).srcs += subsystems/radio_control.c
+  ap.srcs += subsystems/intermcu/intermcu_ap.c
+  ap.srcs += pprzlink/src/pprz_transport.c
+  $(TARGET).srcs += subsystems/radio_control.c
 endif
diff --git a/sw/airborne/subsystems/intermcu/intermcu_fbw.c b/sw/airborne/subsystems/intermcu/intermcu_fbw.c
index 068e5df276..decff4ed0b 100644
--- a/sw/airborne/subsystems/intermcu/intermcu_fbw.c
+++ b/sw/airborne/subsystems/intermcu/intermcu_fbw.c
@@ -182,7 +182,9 @@ static inline void checkPx4RebootCommand(unsigned char b)
       return;
     }
 
+#ifdef SYS_TIME_LED
     LED_ON(SYS_TIME_LED);
+#endif
 
     if (b == px4RebootSequence[px4RebootSequenceCount]) {
       px4RebootSequenceCount++;
@@ -202,9 +204,16 @@ static inline void checkPx4RebootCommand(unsigned char b)
       intermcu_device->put_byte(intermcu_device->periph,
                                 0x66); // dummy byte, seems to be necessary otherwise one byte is missing at the fmu side...
 
-      while (((struct uart_periph *)(intermcu_device->periph))->tx_running) {LED_TOGGLE(SYS_TIME_LED);}  // tx_running is volatile now, so LED_TOGGLE not necessary anymore
+      while (((struct uart_periph *)(intermcu_device->periph))->tx_running) {
+        // tx_running is volatile now, so LED_TOGGLE not necessary anymore
+#ifdef SYS_TIME_LED
+        LED_TOGGLE(SYS_TIME_LED);
+#endif
+      }
 
+#ifdef SYS_TIME_LED
       LED_OFF(SYS_TIME_LED);
+#endif
       scb_reset_system();
     }
   }