diff --git a/lib/dns/include/dns/name.h b/lib/dns/include/dns/name.h
index 7a67de0c9b..b7f4dcef94 100644
--- a/lib/dns/include/dns/name.h
+++ b/lib/dns/include/dns/name.h
@@ -254,12 +254,16 @@ dns_name_setbuffer(dns_name_t *name, isc_buffer_t *buffer);
  *	The caller must not write to buffer until the name has been
  *	invalidated or is otherwise known not to be in use.
  *
+ *	If buffer is NULL and the name previously had a dedicated buffer,
+ *	than that buffer is no longer dedicated to use with this name.
+ *	The caller is responsible for ensuring that the storage used by
+ *	the name remains valid.
+ *
  * Requires:
  *	'name' is a valid name.
  *
- *	'name' doesn't have a dedicated buffer already.
- *
- *	'buffer' is a valid binary buffer.
+ *	'buffer' is a valid binary buffer and 'name' doesn't have a
+ *	dedicated buffer already, or 'buffer' is NULL.
  */
 
 isc_boolean_t
diff --git a/lib/dns/name.c b/lib/dns/name.c
index d702a93c29..a0051b32fe 100644
--- a/lib/dns/name.c
+++ b/lib/dns/name.c
@@ -289,8 +289,10 @@ dns_name_setbuffer(dns_name_t *name, isc_buffer_t *buffer) {
 	 */
 
 	REQUIRE(VALID_NAME(name));
-	REQUIRE(name->buffer == NULL);
-	REQUIRE(isc_buffer_type(buffer) == ISC_BUFFERTYPE_BINARY);
+	REQUIRE((buffer != NULL &&
+		 name->buffer == NULL &&
+		 isc_buffer_type(buffer) == ISC_BUFFERTYPE_BINARY) ||
+		(buffer == NULL));
 
 	name->buffer = buffer;
 }