diff --git a/src/test/recovery/t/035_standby_logical_decoding.pl b/src/test/recovery/t/035_standby_logical_decoding.pl
index c31cab06f1c..edd8009fbce 100644
--- a/src/test/recovery/t/035_standby_logical_decoding.pl
+++ b/src/test/recovery/t/035_standby_logical_decoding.pl
@@ -258,10 +258,20 @@ sub wait_until_vacuum_can_remove
 	# Launch our sql.
 	$node_primary->safe_psql('testdb', qq[$sql]);
 
+	$node_primary->safe_psql('testdb',"CHECKPOINT");
+	sleep(20);
+
+	$node_primary->safe_psql(
+	    'testdb', "
+		BEGIN;
+		PREPARE TRANSACTION 'prevent_slot_advance_v1';
+		INSERT INTO prevent_slot_advance VALUES (1);"
+	);
+
 	# Wait until we get a newer horizon.
-	$node_primary->poll_query_until('testdb',
-		"SELECT (select pg_snapshot_xmin(pg_current_snapshot())::text::int - $xid_horizon) > 0"
-	) or die "new snapshot does not have a newer horizon";
+	#$node_primary->poll_query_until('testdb',
+	#	"SELECT (select pg_snapshot_xmin(pg_current_snapshot())::text::int - $xid_horizon) > 0"
+	#) or die "new snapshot does not have a newer horizon";
 
 	# Launch the vacuum command and insert into flush_wal (see CREATE
 	# TABLE flush_wal for the reason).
@@ -281,7 +291,9 @@ wal_level = 'logical'
 max_replication_slots = 4
 max_wal_senders = 4
 autovacuum = off
+max_prepared_transactions = 10
 });
+
 $node_primary->dump_info;
 $node_primary->start;
 
@@ -305,6 +317,7 @@ $node_primary->backup($backup_name);
 # Some tests need to wait for VACUUM to be replayed. But vacuum does not flush
 # WAL. An insert into flush_wal outside transaction does guarantee a flush.
 $node_primary->psql('testdb', q[CREATE TABLE flush_wal();]);
+$node_primary->psql('testdb', q[CREATE TABLE prevent_slot_advance(a int);]);
 
 #######################
 # Initialize standby node
@@ -565,6 +578,8 @@ check_for_invalidation('vacuum_full_', 1, 'with vacuum FULL on pg_class');
 # Verify reason for conflict is 'rows_removed' in pg_replication_slots
 check_slots_conflict_reason('vacuum_full_', 'rows_removed');
 
+$node_primary->safe_psql('testdb', "COMMIT PREPARED 'prevent_slot_advance_v1'");
+
 # Attempting to alter an invalidated slot should result in an error
 ($result, $stdout, $stderr) = $node_standby->psql(
 	'postgres',
@@ -664,6 +679,8 @@ check_for_invalidation('row_removal_', $logstart, 'with vacuum on pg_class');
 # Verify reason for conflict is 'rows_removed' in pg_replication_slots
 check_slots_conflict_reason('row_removal_', 'rows_removed');
 
+$node_primary->safe_psql('testdb', "COMMIT PREPARED 'prevent_slot_advance_v1'");
+
 $handle =
   make_slot_active($node_standby, 'row_removal_', 0, \$stdout, \$stderr);
 
@@ -699,6 +716,8 @@ check_for_invalidation('shared_row_removal_', $logstart,
 # Verify reason for conflict is 'rows_removed' in pg_replication_slots
 check_slots_conflict_reason('shared_row_removal_', 'rows_removed');
 
+$node_primary->safe_psql('testdb', "COMMIT PREPARED 'prevent_slot_advance_v1'");
+
 $handle = make_slot_active($node_standby, 'shared_row_removal_', 0, \$stdout,
 	\$stderr);
 
@@ -737,6 +756,8 @@ ok( !$node_standby->log_contains(
 	'activeslot slot invalidation is not logged with vacuum on conflict_test'
 );
 
+$node_primary->safe_psql('testdb', "COMMIT PREPARED 'prevent_slot_advance_v1'");
+
 # Verify that pg_stat_database_conflicts.confl_active_logicalslot has not been updated
 ok( $node_standby->poll_query_until(
 		'postgres',