diff --git a/CHANGES b/CHANGES
index 3368f4c428..05f3e725c0 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,7 @@
+3027.	[bug]		Add documented REQUIREs to cfg_obj_asnetprefix() to
+			catch NULL pointer dereferences before they happen.
+			[RT #22521]
+
 3026.	[bug]		lib/isc/httpd.c: check that we have enough space
 			after calling grow_headerspace() and if not
 			re-call grow_headerspace() until we do. [RT #22521]
diff --git a/lib/isccfg/parser.c b/lib/isccfg/parser.c
index 7db753e2cb..70126fc973 100644
--- a/lib/isccfg/parser.c
+++ b/lib/isccfg/parser.c
@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: parser.c,v 1.139 2011/01/04 23:47:14 tbox Exp $ */
+/* $Id: parser.c,v 1.140 2011/02/21 06:07:49 marka Exp $ */
 
 /*! \file */
 
@@ -2006,8 +2006,12 @@ cfg_obj_isnetprefix(const cfg_obj_t *obj) {
 
 void
 cfg_obj_asnetprefix(const cfg_obj_t *obj, isc_netaddr_t *netaddr,
-		    unsigned int *prefixlen) {
+		    unsigned int *prefixlen)
+{
 	REQUIRE(obj != NULL && obj->type->rep == &cfg_rep_netprefix);
+	REQUIRE(netaddr != NULL);
+	REQUIRE(prefixlen != NULL);
+
 	*netaddr = obj->value.netprefix.address;
 	*prefixlen = obj->value.netprefix.prefixlen;
 }