diff --git a/src/cpu.h b/src/cpu.h
index c9e6ce4..a666a07 100644
--- a/src/cpu.h
+++ b/src/cpu.h
@@ -112,6 +112,7 @@
   is larger than necessary to avoid additional checks on the validity of
   the R register index fields during emulation
   ---------------------------------------------------------------------------*/
+#include "machdep.h"
 
 /* General */
 #define NIBBLE_PER_REGISTER 16