diff --git a/doc/misc/options b/doc/misc/options
index fb0bf6563a..53b569d714 100644
--- a/doc/misc/options
+++ b/doc/misc/options
@@ -299,7 +299,7 @@ options {
 	tcp-receive-buffer <integer>;
 	tcp-send-buffer <integer>;
 	tkey-dhkey <quoted_string> <integer>; // deprecated
-	tkey-domain <quoted_string>;
+	tkey-domain <quoted_string>; // deprecated
 	tkey-gssapi-credential <quoted_string>; // deprecated
 	tkey-gssapi-keytab <quoted_string>;
 	tls-port <integer>;
diff --git a/lib/isccfg/namedconf.c b/lib/isccfg/namedconf.c
index e2fc05677c..29699611f6 100644
--- a/lib/isccfg/namedconf.c
+++ b/lib/isccfg/namedconf.c
@@ -1339,7 +1339,7 @@ static cfg_clausedef_t options_clauses[] = {
 	{ "tcp-receive-buffer", &cfg_type_uint32, 0 },
 	{ "tcp-send-buffer", &cfg_type_uint32, 0 },
 	{ "tkey-dhkey", &cfg_type_tkey_dhkey, CFG_CLAUSEFLAG_DEPRECATED },
-	{ "tkey-domain", &cfg_type_qstring, 0 },
+	{ "tkey-domain", &cfg_type_qstring, CFG_CLAUSEFLAG_DEPRECATED },
 	{ "tkey-gssapi-credential", &cfg_type_qstring,
 	  CFG_CLAUSEFLAG_DEPRECATED },
 	{ "tkey-gssapi-keytab", &cfg_type_qstring, 0 },