diff --git a/branches/follower/wiz810mj/src/lib/types.h b/branches/follower/wiz810mj/src/lib/types.h
index e5b01b0..20b93ca 100644
--- a/branches/follower/wiz810mj/src/lib/types.h
+++ b/branches/follower/wiz810mj/src/lib/types.h
@@ -16,6 +16,14 @@
 #define __MCU_AVR__	1
 #define __MCU_TYPE__	__MCU_AVR__
 
+// TODO: We should really specify the Chip Select pin based on
+// the MCU rather than the platform.
+#ifdef __ARDUINO__
+#define CS_PIN PB2
+#else
+#define CS_PIN PB0
+#endif
+
 //---- Refer "Rom File Maker Manual Vx.x.pdf"
 #include <avr/pgmspace.h>