diff --git a/src/vim.h b/src/vim.h
index 1011be7..4107f6b 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -2518,6 +2518,7 @@
 #define ERROR_NONE	5
 #define ERROR_OTHER	6
 #define ERROR_DELETED	7
+#define ERROR_NOTMETHOD	8   // function cannot be used as a method
 
 /* flags for find_name_end() */
 #define FNE_INCL_BR	1	/* include [] in name */