diff --git a/include/types/arg.h b/include/types/arg.h
index 80e0b0a..60fd007 100644
--- a/include/types/arg.h
+++ b/include/types/arg.h
@@ -82,6 +82,7 @@
 	ARGC_SPOE,     /* spoe message args */
 	ARGC_UBK,      /* use_backend message */
 	ARGC_USRV,     /* use-server message */
+	ARGC_HERR,     /* http-error */
 };
 
 /* flags used when compiling and executing regex */