Get unix version compling.
diff --git a/unix/mpyconfig.h b/unix/mpyconfig.h
index 3ab17e6..605b232 100644
--- a/unix/mpyconfig.h
+++ b/unix/mpyconfig.h
@@ -8,6 +8,8 @@
 
 // type definitions for the specific machine
 
+#define BYTES_PER_WORD (8)
+
 typedef int64_t machine_int_t; // must be pointer size
 typedef uint64_t machine_uint_t; // must be pointer size
 typedef void *machine_ptr_t; // must be of pointer size