diff --git a/servers/slapd/schema_init.c b/servers/slapd/schema_init.c
index bf1075f0920a997579548e3aee954e655fbd1308..e62ac3dff6910ced64d2010a50798d7762e68178 100644
--- a/servers/slapd/schema_init.c
+++ b/servers/slapd/schema_init.c
@@ -6771,7 +6771,7 @@ static slap_mrule_defs_rec mrule_defs[] = {
 
 	{"( 1.3.6.1.4.1.4203.666.11.2.3 NAME 'CSNOrderingMatch' "
 		"SYNTAX 1.3.6.1.4.1.4203.666.11.2.1 )",
-		SLAP_MR_HIDE | SLAP_MR_ORDERING | SLAP_MR_ORDERED_INDEX, NULL,
+		SLAP_MR_HIDE | SLAP_MR_ORDERING | SLAP_MR_EXT | SLAP_MR_ORDERED_INDEX, NULL,
 		NULL, csnNormalize, csnOrderingMatch,
 		NULL, NULL,
 		"CSNMatch" },