diff -r f9dd607dc04c Modules/_datetimemodule.c
--- a/Modules/_datetimemodule.c	Tue Jan 03 02:01:42 2017 +0100
+++ b/Modules/_datetimemodule.c	Tue Jan 03 14:58:16 2017 +0100
@@ -120,6 +120,8 @@ static PyTypeObject PyDateTime_TimeType;
 static PyTypeObject PyDateTime_TZInfoType;
 static PyTypeObject PyDateTime_TimeZoneType;

+static int check_tzinfo_subclass(PyObject *p);
+
 _Py_IDENTIFIER(as_integer_ratio);
 _Py_IDENTIFIER(fromutc);
 _Py_IDENTIFIER(isoformat);
@@ -672,6 +674,10 @@ new_date_ex(int year, int month, int day
 {
     PyDateTime_Date *self;

+    if (check_date_args(year, month, day) < 0) {
+        return NULL;
+    }
+
     self = (PyDateTime_Date *) (type->tp_alloc(type, 0));
     if (self != NULL)
         set_date_fields(self, year, month, day);
@@ -689,6 +695,16 @@ new_datetime_ex2(int year, int month, in
     PyDateTime_DateTime *self;
     char aware = tzinfo != Py_None;

+    if (check_date_args(year, month, day) < 0) {
+        return NULL;
+    }
+    if (check_time_args(hour, minute, second, usecond, fold) < 0) {
+        return NULL;
+    }
+    if (check_tzinfo_subclass(tzinfo) < 0) {
+        return NULL;
+    }
+
     self = (PyDateTime_DateTime *) (type->tp_alloc(type, aware));
     if (self != NULL) {
         self->hastzinfo = aware;
@@ -726,6 +742,13 @@ new_time_ex2(int hour, int minute, int s
     PyDateTime_Time *self;
     char aware = tzinfo != Py_None;

+    if (check_time_args(hour, minute, second, usecond, fold) < 0) {
+        return NULL;
+    }
+    if (check_tzinfo_subclass(tzinfo) < 0) {
+        return NULL;
+    }
+
     self = (PyDateTime_Time *) (type->tp_alloc(type, aware));
     if (self != NULL) {
         self->hastzinfo = aware;
@@ -2511,8 +2534,6 @@ date_new(PyTypeObject *type, PyObject *a

     if (PyArg_ParseTupleAndKeywords(args, kw, "iii", date_kws,
                                     &year, &month, &day)) {
-        if (check_date_args(year, month, day) < 0)
-            return NULL;
         self = new_date_ex(year, month, day, type);
     }
     return self;
@@ -3598,10 +3619,6 @@ time_new(PyTypeObject *type, PyObject *a
     if (PyArg_ParseTupleAndKeywords(args, kw, "|iiiiO$i", time_kws,
                                     &hour, &minute, &second, &usecond,
                                     &tzinfo, &fold)) {
-        if (check_time_args(hour, minute, second, usecond, fold) < 0)
-            return NULL;
-        if (check_tzinfo_subclass(tzinfo) < 0)
-            return NULL;
         self = new_time_ex2(hour, minute, second, usecond, tzinfo, fold,
                             type);
     }
@@ -4188,12 +4205,6 @@ datetime_new(PyTypeObject *type, PyObjec
     if (PyArg_ParseTupleAndKeywords(args, kw, "iii|iiiiO$i", datetime_kws,
                                     &year, &month, &day, &hour, &minute,
                                     &second, &usecond, &tzinfo, &fold)) {
-        if (check_date_args(year, month, day) < 0)
-            return NULL;
-        if (check_time_args(hour, minute, second, usecond, fold) < 0)
-            return NULL;
-        if (check_tzinfo_subclass(tzinfo) < 0)
-            return NULL;
         self = new_datetime_ex2(year, month, day,
                                 hour, minute, second, usecond,
                                 tzinfo, fold, type);
@@ -4269,6 +4280,13 @@ datetime_from_timet_and_us(PyObject *cls
      */
     second = Py_MIN(59, tm.tm_sec);

+    /* reject too old or too recent date to avoid overflow
+       when computing fold */
+    if (check_date_args(year, month, day) < 0) {
+        return NULL;
+    }
+
+    /* local timezone requires to compute fold */
     if (tzinfo == Py_None && f == _PyTime_localtime) {
         long long probe_seconds, result_seconds, transition;

@@ -4528,12 +4546,13 @@ add_datetime_timedelta(PyDateTime_DateTi

     assert(factor == 1 || factor == -1);
     if (normalize_datetime(&year, &month, &day,
-                           &hour, &minute, &second, &microsecond) < 0)
+                           &hour, &minute, &second, &microsecond) < 0) {
         return NULL;
-    else
-        return new_datetime(year, month, day,
-                            hour, minute, second, microsecond,
-                            HASTZINFO(date) ? date->tzinfo : Py_None, 0);
+    }
+
+    return new_datetime(year, month, day,
+                        hour, minute, second, microsecond,
+                        HASTZINFO(date) ? date->tzinfo : Py_None, 0);
 }

 static PyObject *