diff --git a/ghc/includes/Constants.h b/ghc/includes/Constants.h
index dc6d3bdbe9457d5cadf1c86f4dffffc901c9813a..d0640f796e92ca0d3839c308a2fe9c8e17e0fbbd 100644
--- a/ghc/includes/Constants.h
+++ b/ghc/includes/Constants.h
@@ -1,5 +1,5 @@
 /* ----------------------------------------------------------------------------
- * $Id: Constants.h,v 1.11 2000/02/28 12:02:32 sewardj Exp $
+ * $Id: Constants.h,v 1.12 2000/07/26 13:27:54 simonmar Exp $
  *
  * (c) The GHC Team, 1998-1999
  *
@@ -158,6 +158,10 @@
 #define INT64_SIZE 	2
 #endif
 
+
+/*---- The size of StgWord, in bytes. */
+#define WORD_SIZE       SIZEOF_VOID_P
+
 /*---- Maximum number of constructors in a data type for direct-returns.  */
 
 #define MAX_VECTORED_RTN 8