diff --git a/radio/src/targets/common/arm/stm32/CMakeLists.txt b/radio/src/targets/common/arm/stm32/CMakeLists.txt
index 2022fdcc3..c050f9e94 100644
--- a/radio/src/targets/common/arm/stm32/CMakeLists.txt
+++ b/radio/src/targets/common/arm/stm32/CMakeLists.txt
@@ -18,6 +18,7 @@ include_directories(${STM32USB_DIR}/STM32_USB_Device_Library/Class/hid/inc)
 include_directories(${STM32USB_DIR}/STM32_USB_Device_Library/Class/cdc/inc)
 include_directories(${STM32USB_DIR}/STM32_USB_Device_Library/Core/inc/)
 include_directories(${STM32USB_DIR}/STM32_USB_OTG_Driver/inc)
+
 set(STM32USB_SRC
   STM32_USB_OTG_Driver/src/usb_core.c
   STM32_USB_OTG_Driver/src/usb_dcd.c
@@ -26,20 +27,19 @@ set(STM32USB_SRC
   STM32_USB_Device_Library/Core/src/usbd_ioreq.c
   STM32_USB_Device_Library/Core/src/usbd_req.c
   )
+
 set(FIRMWARE_TARGET_SRC
   ${FIRMWARE_TARGET_SRC}
   ../common/arm/stm32/rtc_driver.cpp
-  ../common/arm/stm32/cpu_id.cpp
   ${AUX_SERIAL_DRIVER}
-  )
-set(FIRMWARE_TARGET_SRC
-  ${FIRMWARE_TARGET_SRC}
   ../common/arm/stm32/delays.cpp
   ../common/arm/stm32/usb_bsp.c
   ../common/arm/stm32/usbd_desc.c
   ../common/arm/stm32/usbd_usr.cpp
   ../common/arm/stm32/usb_driver.cpp
   ../common/arm/stm32/flash_driver.cpp
+  ../common/arm/stm32/usbd_storage_msd.cpp
+  ../common/arm/stm32/usbd_hid_joystick.c
   )
 
 if(DEBUG OR CLI OR USB_SERIAL)
@@ -62,16 +62,6 @@ set(STM32USB_SRC
   STM32_USB_Device_Library/Class/msc/src/usbd_msc_core.c
   )
 
-set(FIRMWARE_TARGET_SRC
-  ${FIRMWARE_TARGET_SRC}
-  ../common/arm/stm32/usbd_storage_msd.cpp
-  )
-
-set(FIRMWARE_TARGET_SRC
-  ${FIRMWARE_TARGET_SRC}
-  ../common/arm/stm32/usbd_hid_joystick.c
-  )
-
 if(GVARS)
   set(GUI_SRC
     ${GUI_SRC}
@@ -99,6 +89,11 @@ foreach(FILE ${STM32USB_SRC})
     )
 endforeach()
 
+set(TARGET_SRC
+  ${TARGET_SRC}
+  ../common/arm/stm32/cpu_id.cpp
+  )
+
 set(SRC
   ${SRC}
   io/bootloader_flash.cpp
diff --git a/radio/src/targets/common/arm/stm32/aux_serial_driver.cpp b/radio/src/targets/common/arm/stm32/aux_serial_driver.cpp
index 93a46e9a6..fc41ae08b 100644
--- a/radio/src/targets/common/arm/stm32/aux_serial_driver.cpp
+++ b/radio/src/targets/common/arm/stm32/aux_serial_driver.cpp
@@ -22,7 +22,7 @@
 
 uint8_t auxSerialMode = 0;
 Fifo<uint8_t, 512> auxSerialTxFifo;
-DMAFifo<32> auxSerialRxFifo __DMA (AUX_SERIAL_DMA_Stream_RX);
+AuxSerialRxFifo auxSerialRxFifo __DMA (AUX_SERIAL_DMA_Stream_RX);
 
 void auxSerialSetup(unsigned int baudrate, bool dma)
 {
diff --git a/radio/src/targets/horus/board.h b/radio/src/targets/horus/board.h
index 7f0df8dae..ff4618b87 100644
--- a/radio/src/targets/horus/board.h
+++ b/radio/src/targets/horus/board.h
@@ -614,7 +614,8 @@ void bluetoothDisable();
 #include "fifo.h"
 #include "dmafifo.h"
 extern DMAFifo<512> telemetryFifo;
-extern DMAFifo<32> auxSerialRxFifo;
+typedef DMAFifo<32> AuxSerialRxFifo;
+extern AuxSerialRxFifo auxSerialRxFifo;
 #endif
 
 #endif // _BOARD_H_
diff --git a/radio/src/targets/simu/simpgmspace.cpp b/radio/src/targets/simu/simpgmspace.cpp
index f639fb961..b9f603b8a 100644
--- a/radio/src/targets/simu/simpgmspace.cpp
+++ b/radio/src/targets/simu/simpgmspace.cpp
@@ -757,3 +757,23 @@ void rtcInit()
 void rtcSetTime(const struct gtm * t)
 {
 }
+
+#if defined(AUX_SERIAL)
+AuxSerialRxFifo auxSerialRxFifo(nullptr);
+uint8_t auxSerialMode;
+void auxSerialInit(unsigned int mode, unsigned int protocol)
+{
+}
+
+void auxSerialPutc(char c)
+{
+}
+
+void auxSerialSbusInit()
+{
+}
+
+void auxSerialStop()
+{
+}
+#endif
diff --git a/radio/src/targets/sky9x/aux_serial_driver.cpp b/radio/src/targets/sky9x/aux_serial_driver.cpp
index e0b41fc6a..13fd88d95 100644
--- a/radio/src/targets/sky9x/aux_serial_driver.cpp
+++ b/radio/src/targets/sky9x/aux_serial_driver.cpp
@@ -99,8 +99,7 @@ void SECOND_UART_Stop()
 
 extern "C" void UART0_IRQHandler()
 {
-  if ( SECOND_SERIAL_UART->UART_SR & UART_SR_RXRDY )
-  {
+  if (SECOND_SERIAL_UART->UART_SR & UART_SR_RXRDY) {
     auxSerialRxFifo.push(SECOND_SERIAL_UART->UART_RHR);
   }
 }
diff --git a/radio/src/targets/taranis/board.h b/radio/src/targets/taranis/board.h
index 4dbb4d85a..a899d3551 100644
--- a/radio/src/targets/taranis/board.h
+++ b/radio/src/targets/taranis/board.h
@@ -850,7 +850,8 @@ void setTopBatteryValue(uint32_t volts);
 #endif
 
 extern Fifo<uint8_t, TELEMETRY_FIFO_SIZE> telemetryFifo;
-extern DMAFifo<32> auxSerialRxFifo;
+typedef DMAFifo<32> AuxSerialRxFifo;
+extern AuxSerialRxFifo auxSerialRxFifo;
 #endif
 
 // Gyro driver