diff -r f9dd607dc04c Modules/timemodule.c
--- a/Modules/timemodule.c	Tue Jan 03 02:01:42 2017 +0100
+++ b/Modules/timemodule.c	Tue Jan 03 13:36:50 2017 +0100
@@ -279,11 +279,21 @@ static PyTypeObject StructTimeType;
 static PyObject *
 tmtotuple(struct tm *p
 #ifndef HAVE_STRUCT_TM_TM_ZONE
-        , const char *zone, int gmtoff
+        , const char *zone, time_t gmtoff
 #endif
 )
 {
-    PyObject *v = PyStructSequence_New(&StructTimeType);
+    PyObject *v;
+
+#ifndef HAVE_STRUCT_TM_TM_ZONE
+    if (gmtoff < LONG_MIN || LONG_MAX < gmtoff) {
+        PyErr_SetString(PyExc_OverflowError,
+                        "tm_gmtoff too large to fit in a C long");
+        return NULL;
+    }
+#endif
+
+    v = PyStructSequence_New(&StructTimeType);
     if (v == NULL)
         return NULL;
 
@@ -397,7 +407,7 @@ time_localtime(PyObject *self, PyObject 
     {
         struct tm local = buf;
         char zone[100];
-        int gmtoff;
+        time_t gmtoff;
         strftime(zone, sizeof(zone), "%Z", &buf);
         gmtoff = timegm(&buf) - when;
         return tmtotuple(&local, zone, gmtoff);
@@ -1173,7 +1183,7 @@ get_zone(char *zone, int n, struct tm *p
 #endif
 }
 
-static int
+static time_t
 get_gmtoff(time_t t, struct tm *p)
 {
 #ifdef HAVE_STRUCT_TM_TM_ZONE