diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 82330cb..375653b 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -618,11 +618,12 @@ main(int argc, char **argv)
 		else
 			ExecuteSqlStatement(fout,
 								"SET TRANSACTION ISOLATION LEVEL "
-								"REPEATABLE READ");
+								"REPEATABLE READ, READ ONLY");
 	}
 	else
 		ExecuteSqlStatement(fout,
-							"SET TRANSACTION ISOLATION LEVEL SERIALIZABLE");
+							"SET TRANSACTION ISOLATION LEVEL "
+							"SERIALIZABLE, READ ONLY");
 
 	/* Select the appropriate subquery to convert user IDs to names */
 	if (fout->remoteVersion >= 80100)