diff --git a/FSH.h b/FSH.h
index f8c0f87..21df20c 100644
--- a/FSH.h
+++ b/FSH.h
@@ -2,6 +2,10 @@
 #define FSH_h
 #include <Arduino.h>
 #ifdef ARDUINO_ARCH_MEGAAVR
+#ifdef F
+#undef F
+#define F(str) (str)
+#endif
 typedef char FSH; 
 #define GETFLASH(addr) (*(const unsigned char *)(addr))
 #define FLASH