diff --git a/trytond/backend/postgresql/database.py b/trytond/backend/postgresql/database.py
index 0ab83431d8..3b3ca51a1c 100644
--- a/trytond/backend/postgresql/database.py
+++ b/trytond/backend/postgresql/database.py
@@ -231,7 +231,7 @@ class Database(DatabaseInterface):
         # psycopg2cffi does not have the readonly property
         if hasattr(conn, 'readonly'):
             conn.readonly = readonly
-        elif not autocommit:
+        elif not autocommit and readonly:
             cursor = conn.cursor()
             cursor.execute('SET TRANSACTION READ ONLY')
         return conn