diff --git a/django/db/backends/postgresql/operations.py b/django/db/backends/postgresql/operations.py
index 14bd976d8b..35824609b2 100644
--- a/django/db/backends/postgresql/operations.py
+++ b/django/db/backends/postgresql/operations.py
@@ -27,9 +27,8 @@ class DatabaseOperations(BaseDatabaseOperations):
     def date_extract_sql(self, lookup_type, field_name):
         # http://www.postgresql.org/docs/8.0/static/functions-datetime.html#FUNCTIONS-DATETIME-EXTRACT
         if lookup_type == 'week_day':
-            # Using EXTRACT(), PostgreSQL days are indexed as Sunday=0, Saturday=6.
-            # If we instead us TO_CHAR, they're indexed with Sunday=1, Saturday=7
-            return "TO_CHAR(%s, 'D')" % field_name
+            # For consistency across backends, we return Sunday=1, Saturday=7.
+            return "EXTRACT('dow' FROM %s) + 1" % field_name
         else:
             return "EXTRACT('%s' FROM %s)" % (lookup_type, field_name)
 
diff --git a/django/db/backends/sqlite3/base.py b/django/db/backends/sqlite3/base.py
index 8a4c072896..f9be87d00a 100644
--- a/django/db/backends/sqlite3/base.py
+++ b/django/db/backends/sqlite3/base.py
@@ -211,9 +211,9 @@ def _sqlite_extract(lookup_type, dt):
     except (ValueError, TypeError):
         return None
     if lookup_type == 'week_day':
-        return unicode((dt.isoweekday() % 7) + 1)
+        return (dt.isoweekday() % 7) + 1
     else:
-        return unicode(getattr(dt, lookup_type))
+        return getattr(dt, lookup_type)
 
 def _sqlite_date_trunc(lookup_type, dt):
     try:
diff --git a/django/db/models/fields/__init__.py b/django/db/models/fields/__init__.py
index 0c9aa59425..f580384b80 100644
--- a/django/db/models/fields/__init__.py
+++ b/django/db/models/fields/__init__.py
@@ -500,10 +500,10 @@ class DateField(Field):
                 curry(cls._get_next_or_previous_by_FIELD, field=self, is_next=False))
 
     def get_db_prep_lookup(self, lookup_type, value):
-        # For "__month", "__day", and "__week_day" lookups, convert the value 
-        # to a string so the database backend always sees a consistent type.
+        # For "__month", "__day", and "__week_day" lookups, convert the value
+        # to an int so the database backend always sees a consistent type.
         if lookup_type in ('month', 'day', 'week_day'):
-            return [force_unicode(value)]
+            return [int(value)]
         return super(DateField, self).get_db_prep_lookup(lookup_type, value)
 
     def get_db_prep_value(self, value):