diff --git a/libraries/AP_HAL/SPIDriver.h b/libraries/AP_HAL/SPIDriver.h
index a10a4c5513..e9c5a9f418 100644
--- a/libraries/AP_HAL/SPIDriver.h
+++ b/libraries/AP_HAL/SPIDriver.h
@@ -25,6 +25,7 @@ public:
     virtual void cs_assert() = 0;
     virtual void cs_release() = 0;
     virtual uint8_t transfer (uint8_t data) = 0;
+    virtual void transfer (const uint8_t *data, uint16_t len) = 0;
 };
 
 #endif // __AP_HAL_SPI_DRIVER_H__