diff --git a/setup.py b/setup.py
index f561c3c828..a60a203194 100644
--- a/setup.py
+++ b/setup.py
@@ -80,12 +80,9 @@ if os.name == 'nt':
     }
     args['zipfile'] = 'library.zip'
 
-    if sys.version_info < (2, 6):
-        data_files.append(('', ['msvcp71.dll']))
-    else:
-        data_files.append(('', ['msvcr90.dll', 'msvcp90.dll', 'msvcm90.dll']))
-        manifest = read('Microsoft.VC90.CRT.manifest')
-        args['windows'][0]['other_resources'] = [(24, 1, manifest)]
+    data_files.append(('', ['msvcr90.dll', 'msvcp90.dll', 'msvcm90.dll']))
+    manifest = read('Microsoft.VC90.CRT.manifest')
+    args['windows'][0]['other_resources'] = [(24, 1, manifest)]
 
 
 elif os.name == 'mac' \
diff --git a/tryton/common/common.py b/tryton/common/common.py
index c6a69f58fb..cda563fbb5 100644
--- a/tryton/common/common.py
+++ b/tryton/common/common.py
@@ -371,10 +371,7 @@ def file_open(filename, type, parent, print_p=False):
         if print_p:
             operation = 'print'
         try:
-            if sys.version_info[:2] >= (2, 5):
-                os.startfile(os.path.normpath(filename), operation)
-            else:
-                os.startfile(os.path.normpath(filename))
+            os.startfile(os.path.normpath(filename), operation)
         except WindowsError:
             save_name = file_selection(_('Save As...'), parent=parent,
                     action=gtk.FILE_CHOOSER_ACTION_SAVE)
diff --git a/tryton/gui/main.py b/tryton/gui/main.py
index f0bfd6d4c3..1bd14b1201 100644
--- a/tryton/gui/main.py
+++ b/tryton/gui/main.py
@@ -9,10 +9,7 @@ from urlparse import urlparse
 import urllib
 import gobject
 import gtk
-if sys.version_info < (2, 6):
-    import simplejson as json
-else:
-    import json
+import json
 import webbrowser
 import tryton.rpc as rpc
 from tryton.config import CONFIG, TRYTON_ICON, PIXMAPS_DIR, DATA_DIR, \
diff --git a/tryton/gui/window/view_form/view/list.py b/tryton/gui/window/view_form/view/list.py
index 0737e40bab..0e5a02dbe8 100644
--- a/tryton/gui/window/view_form/view/list.py
+++ b/tryton/gui/window/view_form/view/list.py
@@ -3,10 +3,7 @@
 import gobject
 import gtk
 import sys
-if sys.version_info < (2, 6):
-    import simplejson as json
-else:
-    import json
+import json
 import tryton.rpc as rpc
 import locale
 from interface import ParserView
diff --git a/tryton/pyson.py b/tryton/pyson.py
index c4e1399983..2c639052e2 100644
--- a/tryton/pyson.py
+++ b/tryton/pyson.py
@@ -1,10 +1,7 @@
 #This file is part of Tryton.  The COPYRIGHT file at the top level of
 #this repository contains the full copyright notices and license terms.
 import sys
-if sys.version_info < (2, 6):
-    import simplejson as json
-else:
-    import json
+import json
 import datetime
 from functools import reduce