diff -r 430af393d8f1 Lib/test/datetimetester.py
--- a/Lib/test/datetimetester.py	Wed Mar 23 18:45:55 2016 +0100
+++ b/Lib/test/datetimetester.py	Wed Mar 23 14:24:12 2016 -0400
@@ -3463,6 +3463,14 @@
         self.assertEqual(dt, local)
         self.assertEqual(local.strftime("%z %Z"), "-0400 EDT")
 
+    @support.run_with_tz('EST+05EDT,M3.2.0,M11.1.0')
+    def test_astimezone_default_near_fold(self):
+        # Issue #26616.
+        u = datetime(2015, 11, 1, 5, tzinfo=timezone.utc)
+        t = u.astimezone()
+        s = t.astimezone()
+        self.assertEqual(t.tzinfo, s.tzinfo)
+        
     def test_aware_subtract(self):
         cls = self.theclass
 
diff -r 430af393d8f1 Modules/_datetimemodule.c
--- a/Modules/_datetimemodule.c	Wed Mar 23 18:45:55 2016 +0100
+++ b/Modules/_datetimemodule.c	Wed Mar 23 14:24:12 2016 -0400
@@ -4753,7 +4753,12 @@
     PyObject *nameo = NULL;
     const char *zone = NULL;
 
-    delta = datetime_subtract((PyObject *)utc_time, PyDateTime_Epoch);
+    delta = new_delta(ymd_to_ord(GET_YEAR(utc_time), GET_MONTH(utc_time),
+				 GET_DAY(utc_time)) - 719163,
+		      60 * (60 * DATE_GET_HOUR(utc_time) +
+			    DATE_GET_MINUTE(utc_time)) +
+		      DATE_GET_SECOND(utc_time),
+		      0, 0);
     if (delta == NULL)
         return NULL;
     one_second = new_delta(0, 1, 0, 0);