diff --git a/openerp/osv/fields.py b/openerp/osv/fields.py
index 3117793dcab..6c74c05bd5a 100644
--- a/openerp/osv/fields.py
+++ b/openerp/osv/fields.py
@@ -49,7 +49,7 @@ import simplejson
 _logger = logging.getLogger(__name__)
 
 def _symbol_set(symb):
-    if symb == None or symb == False:
+    if symb is None or symb == False:
         return None
     elif isinstance(symb, unicode):
         return symb.encode('utf-8')
@@ -191,7 +191,7 @@ class char(_column):
         # * we need to remove the "symb==False" from the next line BUT
         #   for now too many things rely on this broken behavior
         # * the symb==None test should be common to all data types
-        if symb == None or symb == False:
+        if symb is None or symb == False:
             return None
 
         # we need to convert the string to a unicode object to be able