diff --git a/src/platforms/96b_carbon/platform.c b/src/platforms/96b_carbon/platform.c
index 93e74c9..bc928b3 100644
--- a/src/platforms/96b_carbon/platform.c
+++ b/src/platforms/96b_carbon/platform.c
@@ -25,6 +25,7 @@
 #include "general.h"
 #include "usb.h"
 #include "usbuart.h"
+#include "aux_serial.h"
 #include "morse.h"
 
 #include <libopencm3/stm32/f4/rcc.h>
diff --git a/src/platforms/blackpillv2/platform.c b/src/platforms/blackpillv2/platform.c
index 4b4a6b0..a3807e4 100644
--- a/src/platforms/blackpillv2/platform.c
+++ b/src/platforms/blackpillv2/platform.c
@@ -25,6 +25,7 @@
 #include "general.h"
 #include "usb.h"
 #include "usbuart.h"
+#include "aux_serial.h"
 #include "morse.h"
 
 #include <libopencm3/stm32/rcc.h>
diff --git a/src/platforms/common/aux_serial.c b/src/platforms/common/aux_serial.c
index 2a090b9..418751e 100644
--- a/src/platforms/common/aux_serial.c
+++ b/src/platforms/common/aux_serial.c
@@ -31,6 +31,7 @@
 #include "general.h"
 #include "usbuart.h"
 #include "usb.h"
+#include "aux_serial.h"
 
 void aux_serial_set_encoding(struct usb_cdc_line_coding *coding)
 {
diff --git a/src/platforms/common/aux_serial.h b/src/platforms/common/aux_serial.h
new file mode 100644
index 0000000..2638779
--- /dev/null
+++ b/src/platforms/common/aux_serial.h
@@ -0,0 +1,29 @@
+/*
+ * This file is part of the Black Magic Debug project.
+ *
+ * Copyright (C) 2022 1BitSquared <info@1bitsquared.com>
+ * Written by Rachel Mant <git@dragonmux.network>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef AUX_SERIAL_H
+#define AUX_SERIAL_H
+
+#include <libopencm3/usb/usbd.h>
+#include <libopencm3/usb/cdc.h>
+
+void aux_serial_init(void);
+void aux_serial_set_encoding(struct usb_cdc_line_coding *coding);
+
+#endif /*AUX_SERIAL_H*/
diff --git a/src/platforms/common/usb_serial.c b/src/platforms/common/usb_serial.c
index e55a659..0b8bab0 100644
--- a/src/platforms/common/usb_serial.c
+++ b/src/platforms/common/usb_serial.c
@@ -47,6 +47,7 @@
 #include "traceswo.h"
 #endif
 #include "usbuart.h"
+#include "aux_serial.h"
 
 #include <libopencm3/cm3/cortex.h>
 #include <libopencm3/cm3/nvic.h>
diff --git a/src/platforms/common/usbuart.h b/src/platforms/common/usbuart.h
index edb7cb4..7a4d523 100644
--- a/src/platforms/common/usbuart.h
+++ b/src/platforms/common/usbuart.h
@@ -21,13 +21,9 @@
 #define __USBUART_H
 
 #include <libopencm3/usb/usbd.h>
-#include <libopencm3/usb/cdc.h>
 
 #include "general.h"
 
-void aux_serial_init(void);
-
-void aux_serial_set_encoding(struct usb_cdc_line_coding *coding);
 void usbuart_usb_out_cb(usbd_device *dev, uint8_t ep);
 void usbuart_usb_in_cb(usbd_device *dev, uint8_t ep);
 
diff --git a/src/platforms/f072/platform.c b/src/platforms/f072/platform.c
index f4184d4..ef69899 100644
--- a/src/platforms/f072/platform.c
+++ b/src/platforms/f072/platform.c
@@ -24,6 +24,7 @@
 #include "general.h"
 #include "usb.h"
 #include "usbuart.h"
+#include "aux_serial.h"
 #include "morse.h"
 
 #include <libopencm3/stm32/rcc.h>
diff --git a/src/platforms/f3/platform.c b/src/platforms/f3/platform.c
index 92bb704..3aabf37 100644
--- a/src/platforms/f3/platform.c
+++ b/src/platforms/f3/platform.c
@@ -24,6 +24,7 @@
 #include "general.h"
 #include "usb.h"
 #include "usbuart.h"
+#include "aux_serial.h"
 #include "morse.h"
 
 #include <libopencm3/stm32/f3/rcc.h>
diff --git a/src/platforms/f4discovery/platform.c b/src/platforms/f4discovery/platform.c
index bd402fb..7cb3c23 100644
--- a/src/platforms/f4discovery/platform.c
+++ b/src/platforms/f4discovery/platform.c
@@ -25,6 +25,7 @@
 #include "general.h"
 #include "usb.h"
 #include "usbuart.h"
+#include "aux_serial.h"
 #include "morse.h"
 
 #include <libopencm3/stm32/rcc.h>
diff --git a/src/platforms/hydrabus/platform.c b/src/platforms/hydrabus/platform.c
index 68470fa..7819140 100644
--- a/src/platforms/hydrabus/platform.c
+++ b/src/platforms/hydrabus/platform.c
@@ -25,6 +25,7 @@
 #include "general.h"
 #include "usb.h"
 #include "usbuart.h"
+#include "aux_serial.h"
 #include "morse.h"
 
 #include <libopencm3/stm32/rcc.h>
diff --git a/src/platforms/launchpad-icdi/platform.c b/src/platforms/launchpad-icdi/platform.c
index 75f02af..9d58354 100644
--- a/src/platforms/launchpad-icdi/platform.c
+++ b/src/platforms/launchpad-icdi/platform.c
@@ -18,6 +18,7 @@
 #include "gdb_if.h"
 #include "usb.h"
 #include "usbuart.h"
+#include "aux_serial.h"
 
 #include <libopencm3/lm4f/rcc.h>
 #include <libopencm3/lm4f/nvic.h>
diff --git a/src/platforms/native/platform.c b/src/platforms/native/platform.c
index 9cf2be9..9d22b7c 100644
--- a/src/platforms/native/platform.c
+++ b/src/platforms/native/platform.c
@@ -25,6 +25,7 @@
 #include "general.h"
 #include "usb.h"
 #include "usbuart.h"
+#include "aux_serial.h"
 #include "morse.h"
 
 #include <libopencm3/stm32/rcc.h>
diff --git a/src/platforms/stlink/platform.c b/src/platforms/stlink/platform.c
index 4501b0d..08abe2c 100644
--- a/src/platforms/stlink/platform.c
+++ b/src/platforms/stlink/platform.c
@@ -25,6 +25,7 @@
 #include "general.h"
 #include "usb.h"
 #include "usbuart.h"
+#include "aux_serial.h"
 
 #include <libopencm3/stm32/rcc.h>
 #include <libopencm3/cm3/scb.h>
diff --git a/src/platforms/stm32/usbuart.c b/src/platforms/stm32/usbuart.c
index 794d44e..d295ded 100644
--- a/src/platforms/stm32/usbuart.c
+++ b/src/platforms/stm32/usbuart.c
@@ -31,6 +31,7 @@
 #include "general.h"
 #include "usbuart.h"
 #include "usb.h"
+#include "aux_serial.h"
 
 #ifdef DMA_STREAM0
 #define dma_channel_reset(dma, channel) dma_stream_reset(dma, channel)
diff --git a/src/platforms/swlink/platform.c b/src/platforms/swlink/platform.c
index 70bac0e..5654976 100644
--- a/src/platforms/swlink/platform.c
+++ b/src/platforms/swlink/platform.c
@@ -26,6 +26,7 @@
 #include "general.h"
 #include "usb.h"
 #include "usbuart.h"
+#include "aux_serial.h"
 
 #include <libopencm3/stm32/rcc.h>
 #include <libopencm3/cm3/scb.h>