diff --git a/django/utils/datetime_safe.py b/django/utils/datetime_safe.py
index ed8420eb8e..7eaa5c21ce 100644
--- a/django/utils/datetime_safe.py
+++ b/django/utils/datetime_safe.py
@@ -1,11 +1,11 @@
-# Python's datetime strftime doesn't handle dates before 1900.
-# These classes override date and datetime to support the formatting of a date
-# through its full "proleptic Gregorian" date range.
+# These classes override date and datetime to ensure that strftime('%Y')
+# returns four digits (with leading zeros) on years < 1000.
+# https://bugs.python.org/issue13305
 #
 # Based on code submitted to comp.lang.python by Andrew Dalke
 #
-# >>> datetime_safe.date(1850, 8, 2).strftime("%Y/%m/%d was a %A")
-# '1850/08/02 was a Friday'
+# >>> datetime_safe.date(10, 8, 2).strftime("%Y/%m/%d was a %A")
+# '0010/08/02 was a Monday'
 
 import re
 import time as ttime
@@ -71,11 +71,11 @@ def _findall(text, substr):
 
 
 def strftime(dt, fmt):
-    if dt.year >= 1900:
+    if dt.year >= 1000:
         return super(type(dt), dt).strftime(fmt)
     illegal_formatting = _illegal_formatting.search(fmt)
     if illegal_formatting:
-        raise TypeError("strftime of dates before 1900 does not handle" + illegal_formatting.group(0))
+        raise TypeError("strftime of dates before 1000 does not handle " + illegal_formatting.group(0))
 
     year = dt.year
     # For every non-leap year century, advance by
diff --git a/tests/utils_tests/test_datetime_safe.py b/tests/utils_tests/test_datetime_safe.py
index 5fa08bc4f4..56eec838fa 100644
--- a/tests/utils_tests/test_datetime_safe.py
+++ b/tests/utils_tests/test_datetime_safe.py
@@ -1,17 +1,18 @@
-import unittest
 from datetime import (
     date as original_date, datetime as original_datetime,
     time as original_time,
 )
 
+from django.test import SimpleTestCase
 from django.utils.datetime_safe import date, datetime, time
 
 
-class DatetimeTests(unittest.TestCase):
+class DatetimeTests(SimpleTestCase):
 
     def setUp(self):
-        self.just_safe = (1900, 1, 1)
-        self.just_unsafe = (1899, 12, 31, 23, 59, 59)
+        self.percent_y_safe = (1900, 1, 1)  # >= 1900 required on Windows.
+        self.just_safe = (1000, 1, 1)
+        self.just_unsafe = (999, 12, 31, 23, 59, 59)
         self.just_time = (11, 30, 59)
         self.really_old = (20, 1, 1)
         self.more_recent = (2006, 1, 1)
@@ -34,21 +35,23 @@ class DatetimeTests(unittest.TestCase):
         )
 
     def test_safe_strftime(self):
-        self.assertEqual(date(*self.just_unsafe[:3]).strftime('%Y-%m-%d (weekday %w)'), '1899-12-31 (weekday 0)')
-        self.assertEqual(date(*self.just_safe).strftime('%Y-%m-%d (weekday %w)'), '1900-01-01 (weekday 1)')
+        self.assertEqual(date(*self.just_unsafe[:3]).strftime('%Y-%m-%d (weekday %w)'), '0999-12-31 (weekday 2)')
+        self.assertEqual(date(*self.just_safe).strftime('%Y-%m-%d (weekday %w)'), '1000-01-01 (weekday 3)')
 
         self.assertEqual(
-            datetime(*self.just_unsafe).strftime('%Y-%m-%d %H:%M:%S (weekday %w)'), '1899-12-31 23:59:59 (weekday 0)'
+            datetime(*self.just_unsafe).strftime('%Y-%m-%d %H:%M:%S (weekday %w)'), '0999-12-31 23:59:59 (weekday 2)'
         )
         self.assertEqual(
-            datetime(*self.just_safe).strftime('%Y-%m-%d %H:%M:%S (weekday %w)'), '1900-01-01 00:00:00 (weekday 1)'
+            datetime(*self.just_safe).strftime('%Y-%m-%d %H:%M:%S (weekday %w)'), '1000-01-01 00:00:00 (weekday 3)'
         )
 
         self.assertEqual(time(*self.just_time).strftime('%H:%M:%S AM'), '11:30:59 AM')
 
         # %y will error before this date
-        self.assertEqual(date(*self.just_safe).strftime('%y'), '00')
-        self.assertEqual(datetime(*self.just_safe).strftime('%y'), '00')
+        self.assertEqual(date(*self.percent_y_safe).strftime('%y'), '00')
+        self.assertEqual(datetime(*self.percent_y_safe).strftime('%y'), '00')
+        with self.assertRaisesMessage(TypeError, 'strftime of dates before 1000 does not handle %y'):
+            datetime(*self.just_unsafe).strftime('%y')
 
         self.assertEqual(date(1850, 8, 2).strftime("%Y/%m/%d was a %A"), '1850/08/02 was a Friday')