diff --git a/CHANGES b/CHANGES
index a1fd5c8bea..d4fba9d8c8 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+2815.	[bug]		Exclusively lock the task when freezing a zone.
+			[RT #19838]
+
 2814.	[func]		Provide a definitive error message when a master
 			zone is not loaded. [RT #20757]
  
diff --git a/bin/named/server.c b/bin/named/server.c
index 20d09108bc..b6b02b9727 100644
--- a/bin/named/server.c
+++ b/bin/named/server.c
@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: server.c,v 1.556 2009/11/28 15:57:36 vjs Exp $ */
+/* $Id: server.c,v 1.557 2009/12/23 23:33:09 each Exp $ */
 
 /*! \file */
 
@@ -6359,6 +6359,8 @@ ns_server_freeze(ns_server_t *server, isc_boolean_t freeze, char *args,
 		return (DNS_R_NOTMASTER);
 	}
 
+	result = isc_task_beginexclusive(server->task);
+	RUNTIME_CHECK(result == ISC_R_SUCCESS);
 	frozen = dns_zone_getupdatedisabled(zone);
 	if (freeze) {
 		if (frozen) {
@@ -6398,6 +6400,7 @@ ns_server_freeze(ns_server_t *server, isc_boolean_t freeze, char *args,
 			}
 		}
 	}
+	isc_task_endexclusive(server->task);
 
 	if (msg != NULL && strlen(msg) < isc_buffer_availablelength(text))
 		isc_buffer_putmem(text, (const unsigned char *)msg,