diff --git a/lib/dns/include/dns/zone.h b/lib/dns/include/dns/zone.h
index 3acb5a1983..de9ffda620 100644
--- a/lib/dns/include/dns/zone.h
+++ b/lib/dns/include/dns/zone.h
@@ -468,16 +468,6 @@ dns_zone_idetach(dns_zone_t **zonep);
  *\li	'zonep' to point to a valid zone.
  */
 
-void
-dns_zone_setflag(dns_zone_t *zone, unsigned int flags, bool value);
-/*%<
- *	Sets ('value' == 'true') / clears ('value' == 'IS_FALSE')
- *	zone flags.  Valid flag bits are DNS_ZONE_F_*.
- *
- * Requires
- *\li	'zone' to be a valid zone.
- */
-
 isc_result_t
 dns_zone_getdb(dns_zone_t *zone, dns_db_t **dbp);
 /*%<
diff --git a/lib/dns/win32/libdns.def.in b/lib/dns/win32/libdns.def.in
index 145d47883e..2a702765fc 100644
--- a/lib/dns/win32/libdns.def.in
+++ b/lib/dns/win32/libdns.def.in
@@ -1310,7 +1310,6 @@ dns_zone_setdbtype
 dns_zone_setdialup
 dns_zone_setdnssecsignstats
 dns_zone_setfile
-dns_zone_setflag
 dns_zone_setforwardacl
 dns_zone_setidlein
 dns_zone_setidleout
diff --git a/lib/dns/zone.c b/lib/dns/zone.c
index c0d69c76aa..f621e15898 100644
--- a/lib/dns/zone.c
+++ b/lib/dns/zone.c
@@ -5704,17 +5704,6 @@ dns_zone_getmgr(dns_zone_t *zone) {
 	return (zone->zmgr);
 }
 
-void
-dns_zone_setflag(dns_zone_t *zone, unsigned int flags, bool value) {
-	REQUIRE(DNS_ZONE_VALID(zone));
-
-	if (value) {
-		DNS_ZONE_SETFLAG(zone, flags);
-	} else {
-		DNS_ZONE_CLRFLAG(zone, flags);
-	}
-}
-
 void
 dns_zone_setkasp(dns_zone_t *zone, dns_kasp_t *kasp) {
 	REQUIRE(DNS_ZONE_VALID(zone));