--- a/babel/dates.py
+++ b/babel/dates.py
@@ -924,7 +924,7 @@
     def get_day_of_year(self, date=None):
         if date is None:
             date = self.value
-        return (date - date_(date.year, 1, 1)).days + 1
+        return (date - date.replace(month=1, day=1)).days + 1
 
     def get_week_number(self, day_of_period, day_of_week=None):
         """Return the number of the week of a day within a period. This may be

--- a/babel/tests/dates.py
+++ b/babel/tests/dates.py
@@ -83,6 +83,11 @@
         d = date(2007, 4, 1)
         fmt = dates.DateTimeFormat(d, locale='en_US')
         self.assertEqual('91', fmt['D'])
+    
+    def test_day_of_year_works_with_datetime(self):
+        d = datetime(2007, 4, 1)
+        fmt = dates.DateTimeFormat(d, locale='en_US')
+        self.assertEqual('91', fmt['D'])
 
     def test_day_of_year_first(self):
         d = date(2007, 1, 1)
@@ -230,6 +235,11 @@
                           datetime(2007, 04, 01, 15, 30),
                           "yyyy-MM-dd HH:mm", locale='en_US')
 
+    def test_with_day_of_year_in_pattern_and_datetime_param(self):
+        # format_date should work on datetimes just as well (see #282)
+        d = datetime(2007, 04, 01)
+        self.assertEqual('14', dates.format_date(d, 'w', locale='en_US'))
+
 
 class FormatTimeTestCase(unittest.TestCase):