diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index c3ebb3a..65ccc93 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -1011,7 +1011,7 @@ setup_connection(Archive *AH, DumpOptions *dopt, const char *dumpencoding,
 	ExecuteSqlStatement(AH, "BEGIN");
 	if (AH->remoteVersion >= 90100)
 	{
-		if (dopt->serializable_deferrable)
+		if (dopt->serializable_deferrable && AH->sync_snapshot_id == NULL)
 			ExecuteSqlStatement(AH,
 								"SET TRANSACTION ISOLATION LEVEL "
 								"SERIALIZABLE, READ ONLY, DEFERRABLE");