diff --git a/include/cgen/ChangeLog b/include/cgen/ChangeLog
index b9da0e687..a8d5df9e6 100644
--- a/include/cgen/ChangeLog
+++ b/include/cgen/ChangeLog
@@ -1,3 +1,7 @@
+2010-01-05  Doug Evans  <dje@sebabeach.org>
+
+	* basic-modes.h (MAKEDI): New macro.
+
 2009-10-23  Doug Evans  <dje@sebabeach.org>
 
 	* basic-modes.h: New file.  Moved here from opcodes/cgen-types.h.
diff --git a/include/cgen/basic-modes.h b/include/cgen/basic-modes.h
index 7583ee458..bd87f3acb 100644
--- a/include/cgen/basic-modes.h
+++ b/include/cgen/basic-modes.h
@@ -46,4 +46,7 @@ typedef uint64_t UDI;
 typedef int INT;
 typedef unsigned int UINT;
 
+/* Cover macro to create a 64-bit integer.  */
+#define MAKEDI(hi, lo) ((((DI) (SI) (hi)) << 32) | ((UDI) (USI) (lo)))
+
 #endif /* CGEN_BASIC_MODES_H */