diff --git a/src/vim.h b/src/vim.h
index d882e50..c84d5a5 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -2133,6 +2133,7 @@
 // Flags for assignment functions.
 #define LET_IS_CONST	1   // ":const"
 #define LET_NO_COMMAND	2   // "var = expr" without ":let" or ":const"
+#define LET_REDEFINE	4   // variable can be redefined later
 
 #include "ex_cmds.h"	    // Ex command defines
 #include "spell.h"	    // spell checking stuff