diff --git a/src/SPITransfer.cpp b/src/SPITransfer.cpp
index b304a73..19c0db6 100644
--- a/src/SPITransfer.cpp
+++ b/src/SPITransfer.cpp
@@ -1,3 +1,5 @@
+#include "Arduino.h"
+
 #if not (defined(MBED_H) || defined(__SAM3X8E__)) // These boards are/will not be supported by SPITransfer.h
 
 #include "SPITransfer.h"