diff --git a/generic/bltTree.h b/generic/bltTree.h
index 45a4780..492293d 100644
--- a/generic/bltTree.h
+++ b/generic/bltTree.h
@@ -169,7 +169,11 @@ struct Blt_TreeObjectStruct {
 				 * above. */
     Blt_HashTable keyTable;   /* Per-tree keys. */
     Blt_HashTable *interpKeyPtr; /* The local or interp-wide key table. */
+#ifndef __cplusplus
     int delete;
+#else
+    int delete_blt;
+#endif
     int maxKeyList;            /* Max key list length before hash (default 20). */
 };