diff --git a/flight/PiOS/STM32F10x/pios_spi.c b/flight/PiOS/STM32F10x/pios_spi.c
index 563b12580..bdca1a756 100644
--- a/flight/PiOS/STM32F10x/pios_spi.c
+++ b/flight/PiOS/STM32F10x/pios_spi.c
@@ -284,7 +284,7 @@ int32_t PIOS_SPI_TransferByte(uint8_t spi, uint8_t b)
 * \return -2 if unsupported SPI port selected
 * \return -3 if function has been called during an ongoing DMA transfer
 */
-int32_t PIOS_SPI_TransferBlock(uint8_t spi, uint8_t *send_buffer, uint8_t *receive_buffer, uint16_t len, void *callback)
+int32_t PIOS_SPI_TransferBlock(uint8_t spi, const uint8_t *send_buffer, uint8_t *receive_buffer, uint16_t len, void *callback)
 {
   struct pios_spi_dev * spi_dev;
   DMA_InitTypeDef       dma_init;
diff --git a/flight/PiOS/inc/pios_spi.h b/flight/PiOS/inc/pios_spi.h
index 7d3da8bf3..7f61514ae 100644
--- a/flight/PiOS/inc/pios_spi.h
+++ b/flight/PiOS/inc/pios_spi.h
@@ -44,7 +44,7 @@ extern int32_t PIOS_SPI_Init(void);
 extern int32_t PIOS_SPI_SetClockSpeed(uint8_t spi, SPIPrescalerTypeDef spi_prescaler);
 extern int32_t PIOS_SPI_RC_PinSet(uint8_t spi, uint8_t pin_value);
 extern int32_t PIOS_SPI_TransferByte(uint8_t spi, uint8_t b);
-extern int32_t PIOS_SPI_TransferBlock(uint8_t spi, uint8_t *send_buffer, uint8_t *receive_buffer, uint16_t len, void *callback);
+extern int32_t PIOS_SPI_TransferBlock(uint8_t spi, const uint8_t *send_buffer, uint8_t *receive_buffer, uint16_t len, void *callback);
 extern void    PIOS_SPI_IRQ_Handler(uint8_t spi);
 
 #endif /* PIOS_SPI_H */