diff --git a/servers/slapd/back-bdb/index.c b/servers/slapd/back-bdb/index.c
index 907b058902..5a7b2a49b0 100644
--- a/servers/slapd/back-bdb/index.c
+++ b/servers/slapd/back-bdb/index.c
@@ -112,6 +112,7 @@ int bdb_index_param(
 	switch( ftype ) {
 	case LDAP_FILTER_PRESENT:
 		if( IS_SLAP_INDEX( mask, SLAP_INDEX_PRESENT ) ) {
+			*prefixp = presence_key;
 			goto done;
 		}
 		break;