diff --git a/servers/slapd/back-bdb/filterindex.c b/servers/slapd/back-bdb/filterindex.c
index bab0fbadf1..3583831b2b 100644
--- a/servers/slapd/back-bdb/filterindex.c
+++ b/servers/slapd/back-bdb/filterindex.c
@@ -178,6 +178,10 @@ bdb_filter_candidates(
 		Debug( LDAP_DEBUG_FILTER, "\tUNKNOWN %lu\n",
 			(unsigned long) f->f_choice, 0, 0 );
 #endif
+		/* Must not return NULL, otherwise extended filters break */
+		{ struct bdb_info *bdb = (struct bdb_info *) op->o_bd->be_private;
+		BDB_IDL_ALL( bdb, ids );
+		}
 	}
 
 #ifdef NEW_LOGGING