diff --git a/src/vim.h b/src/vim.h
index fe23958..45cf8ca 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -2379,6 +2379,7 @@
 #define ASSIGN_FOR_LOOP 0x40 // assigning to loop variable
 #define ASSIGN_INIT	0x80 // not assigning a value, just a declaration
 #define ASSIGN_UPDATE_BLOCK_ID 0x100  // update sav_block_id
+#define ASSIGN_COMPOUND_OP 0x200  // compound operator e.g. "+="
 
 #include "ex_cmds.h"	    // Ex command defines
 #include "spell.h"	    // spell checking stuff