diff --git a/src/platforms/common/aux_serial.c b/src/platforms/common/aux_serial.c
index e9e31ec..1057a03 100644
--- a/src/platforms/common/aux_serial.c
+++ b/src/platforms/common/aux_serial.c
@@ -37,6 +37,7 @@
 #include "usb.h"
 #include "aux_serial.h"
 
+static char aux_serial_receive_buffer[AUX_UART_BUFFER_SIZE];
 /* Fifo in pointer, writes assumed to be atomic, should be only incremented within RX ISR */
 static uint8_t aux_serial_receive_write_index;
 /* Fifo out pointer, writes assumed to be atomic, should be only incremented outside RX ISR */
diff --git a/src/platforms/common/usbuart.h b/src/platforms/common/usbuart.h
index 932de0b..ec4f79d 100644
--- a/src/platforms/common/usbuart.h
+++ b/src/platforms/common/usbuart.h
@@ -40,12 +40,9 @@ void debug_uart_run(void);
 #define USART_DMA_BUF_SIZE  (1U << USART_DMA_BUF_SHIFT)
 #define AUX_UART_BUFFER_SIZE (USART_DMA_BUF_SIZE)
 
-/* RX Fifo buffer with space for copy fn overrun */
-extern char aux_serial_receive_buffer[AUX_UART_BUFFER_SIZE + sizeof(uint64_t)];
-
 #ifdef ENABLE_DEBUG
 /* Debug Fifo buffer with space for copy fn overrun */
-extern char usb_dbg_buf[AUX_UART_BUFFER_SIZE + sizeof(uint64_t)];
+extern char usb_dbg_buf[AUX_UART_BUFFER_SIZE];
 /* Debug Fifo in pointer */
 extern uint8_t usb_dbg_in;
 /* Debug Fifo out pointer */
@@ -53,9 +50,6 @@ extern uint8_t usb_dbg_out;
 #endif
 #elif defined(LM4F)
 #define AUX_UART_BUFFER_SIZE 128
-
-/* RX Fifo buffer */
-extern char aux_serial_receive_buffer[AUX_UART_BUFFER_SIZE];
 #endif
 
 #endif
diff --git a/src/platforms/stm32/usbuart.c b/src/platforms/stm32/usbuart.c
index 6e4fdb9..6df3621 100644
--- a/src/platforms/stm32/usbuart.c
+++ b/src/platforms/stm32/usbuart.c
@@ -38,12 +38,9 @@
 #define DMA_CGIF DMA_IFCR_CGIF_BIT
 #endif
 
-/* RX Fifo buffer with space for copy fn overrun */
-char aux_serial_receive_buffer[AUX_UART_BUFFER_SIZE + sizeof(uint64_t)];
-
 #ifdef ENABLE_DEBUG
 /* Debug Fifo buffer with space for copy fn overrun */
-char usb_dbg_buf[AUX_UART_BUFFER_SIZE + sizeof(uint64_t)];
+char usb_dbg_buf[AUX_UART_BUFFER_SIZE];
 /* Debug Fifo in pointer */
 uint8_t usb_dbg_in;
 /* Debug Fifo out pointer */
diff --git a/src/platforms/tm4c/usbuart.c b/src/platforms/tm4c/usbuart.c
index 85c099a..6401015 100644
--- a/src/platforms/tm4c/usbuart.c
+++ b/src/platforms/tm4c/usbuart.c
@@ -28,6 +28,3 @@
 
 #include "general.h"
 #include "usb.h"
-
-/* RX Fifo buffer */
-char aux_serial_receive_buffer[AUX_UART_BUFFER_SIZE];