diff --git a/gluon/dal.py b/gluon/dal.py
index d73720cf2..95476a9f2 100644
--- a/gluon/dal.py
+++ b/gluon/dal.py
@@ -75,10 +75,10 @@ def _default_validators(db, field):
     if field.unique:
         requires.insert(0, validators.IS_NOT_IN_DB(db, field))
     excluded_fields = ['string', 'upload', 'text', 'password', 'boolean']
-    if (field.notnull or field.unique) and not field_type in excluded_fields:
+    if (field.notnull or field.unique) and field_type not in excluded_fields:
         requires.insert(0, validators.IS_NOT_EMPTY())
     elif not field.notnull and not field.unique and requires:
-        requires[0] = validators.IS_EMPTY_OR(requires[0], null='' if field in ('string', 'text', 'password') else None)
+        requires[0] = validators.IS_EMPTY_OR(requires[0], null='' if field.type in ('string', 'text', 'password') else None)
     return requires
 
 from gluon.serializers import custom_json, xml