diff --git a/Lib/test/test_itertools.py b/Lib/test/test_itertools.py
index 4b631dd..6898725 100644
--- a/Lib/test/test_itertools.py
+++ b/Lib/test/test_itertools.py
@@ -371,6 +371,7 @@
 
         # test values of n
         self.assertRaises(TypeError, tee, 'abc', 'invalid')
+        self.assertRaises(ValueError, tee, [], -1)
         for n in xrange(5):
             result = tee('abc', n)
             self.assertEqual(type(result), tuple)
diff --git a/Misc/NEWS b/Misc/NEWS
index fe3ed79..794ccc1 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -27,6 +27,8 @@
 
 - Bug #1548092: fix curses.tparm seg fault on invalid input.
 
+- Bug #1550714: fix SystemError from itertools.tee on negative value for n.
+
 
 Tests
 -----
diff --git a/Modules/itertoolsmodule.c b/Modules/itertoolsmodule.c
index d913890..a41f55b 100644
--- a/Modules/itertoolsmodule.c
+++ b/Modules/itertoolsmodule.c
@@ -618,11 +618,15 @@
 static PyObject *
 tee(PyObject *self, PyObject *args)
 {
-	int i, n=2;
+	Py_ssize_t i, n=2;
 	PyObject *it, *iterable, *copyable, *result;
 
-	if (!PyArg_ParseTuple(args, "O|i", &iterable, &n))
+	if (!PyArg_ParseTuple(args, "O|n", &iterable, &n))
 		return NULL;
+	if (n < 0) {
+		PyErr_SetString(PyExc_ValueError, "n must be >= 0");
+		return NULL;
+	}
 	result = PyTuple_New(n);
 	if (result == NULL)
 		return NULL;