diff --git a/servers/slapd/at.c b/servers/slapd/at.c
index deb920b69e..63344d0a91 100644
--- a/servers/slapd/at.c
+++ b/servers/slapd/at.c
@@ -441,6 +441,7 @@ at_add(
 	 */
 	if ( sat->sat_sup ) {
 		sat->sat_syntax = sat->sat_sup->sat_syntax;
+		sat->sat_syntax_compat = sat->sat_sup->sat_syntax_compat;
 
 		sat->sat_equality = sat->sat_sup->sat_equality;
 		sat->sat_ordering = sat->sat_sup->sat_ordering;