diff --git a/lib/dns/db.c b/lib/dns/db.c
index be9492fcfd..8a25990bee 100644
--- a/lib/dns/db.c
+++ b/lib/dns/db.c
@@ -25,6 +25,7 @@
 #include <string.h>
 
 #include <isc/assertions.h>
+#include <isc/ondestroy.h>
 
 #include <dns/db.h>
 #include <dns/master.h>
@@ -118,6 +119,15 @@ dns_db_detach(dns_db_t **dbp) {
 	ENSURE(*dbp == NULL);
 }
 
+isc_result_t
+dns_db_ondestroy(dns_db_t *db, isc_task_t *task, isc_event_t **eventp)
+{
+	REQUIRE(DNS_DB_VALID(db));
+
+	return (isc_ondestroy_register(&db->ondest, task, eventp));
+}
+
+
 isc_boolean_t
 dns_db_iscache(dns_db_t *db) {
 
diff --git a/lib/dns/include/dns/db.h b/lib/dns/include/dns/db.h
index bc7a9aa1e7..fd7e481d8e 100644
--- a/lib/dns/include/dns/db.h
+++ b/lib/dns/include/dns/db.h
@@ -164,6 +164,7 @@ struct dns_db {
 	isc_uint16_t			attributes;
 	dns_rdataclass_t		rdclass;
 	dns_name_t			origin;
+	isc_ondestroy_t			ondest;
 	isc_mem_t *			mctx;
 };
 
@@ -267,6 +268,17 @@ dns_db_detach(dns_db_t **dbp);
  *		All resources used by the database will be freed
  */
 
+isc_result_t
+dns_db_ondestroy(dns_db_t *db, isc_task_t *task, isc_event_t **eventp);
+/*
+ * Causes 'eventp' to be sent to be sent to 'task' when the database is
+ * destroyed.
+ *
+ * Note; ownrship of the eventp is taken from the caller (and *eventp is
+ * set to NULL). The sender field of the event is set to 'db' before it is
+ * sent to the task.
+ */
+
 isc_boolean_t
 dns_db_iscache(dns_db_t *db);
 /*
diff --git a/lib/dns/include/dns/events.h b/lib/dns/include/dns/events.h
index 92b85c74a1..c3e0f05070 100644
--- a/lib/dns/include/dns/events.h
+++ b/lib/dns/include/dns/events.h
@@ -45,6 +45,7 @@ ISC_LANG_BEGINDECLS
 #define DNS_EVENT_CACHECLEAN			(ISC_EVENTCLASS_DNS + 15)
 #define DNS_EVENT_BYADDRDONE			(ISC_EVENTCLASS_DNS + 16)
 #define DNS_EVENT_ZONECONTROL			(ISC_EVENTCLASS_DNS + 17)
+#define DNS_EVENT_DBDESTROYED			(ISC_EVENTCLASS_DNS + 18)
 
 #define DNS_EVENT_FIRSTEVENT			(ISC_EVENTCLASS_DNS + 0)
 #define DNS_EVENT_LASTEVENT			(ISC_EVENTCLASS_DNS + 65535)
diff --git a/lib/dns/rbtdb.c b/lib/dns/rbtdb.c
index 5984ee61b7..b31c793364 100644
--- a/lib/dns/rbtdb.c
+++ b/lib/dns/rbtdb.c
@@ -313,6 +313,7 @@ static void
 free_rbtdb(dns_rbtdb_t *rbtdb) {
 	unsigned int i;
 	isc_region_t r;
+	isc_ondestroy_t ondest;
 
 	REQUIRE(EMPTY(rbtdb->open_versions));
 	REQUIRE(rbtdb->future_version == NULL);
@@ -332,7 +333,9 @@ free_rbtdb(dns_rbtdb_t *rbtdb) {
 	isc_mutex_destroy(&rbtdb->lock);
 	rbtdb->common.magic = 0;
 	rbtdb->common.impmagic = 0;
+	ondest = rbtdb->common.ondest;
 	isc_mem_put(rbtdb->common.mctx, rbtdb, sizeof *rbtdb);
+	isc_ondestroy_notify(&ondest, rbtdb);
 }
 
 static inline void
@@ -3924,6 +3927,8 @@ dns_rbtdb_create
 	rbtdb->future_version = NULL;
 	ISC_LIST_INIT(rbtdb->open_versions);
 
+	isc_ondestroy_init(&rbtdb->common.ondest);
+	
 	rbtdb->common.magic = DNS_DB_MAGIC;
 	rbtdb->common.impmagic = RBTDB_MAGIC;