diff --git a/Lib/test/test_datetime.py b/Lib/test/test_datetime.py
index 89c126fec1c..b827658579f 100644
--- a/Lib/test/test_datetime.py
+++ b/Lib/test/test_datetime.py
@@ -2749,6 +2749,7 @@ class TestDateTimeTZ(TestDateTime, TZInfoBase, unittest.TestCase):
                 self.assertEqual(iso, datestr + 'T' + tailstr)
                 self.assertEqual(iso, d.isoformat('T'))
                 self.assertEqual(d.isoformat('k'), datestr + 'k' + tailstr)
+                self.assertEqual(d.isoformat('\u1234'), datestr + '\u1234' + tailstr)
                 self.assertEqual(str(d), datestr + ' ' + tailstr)
 
     def test_replace(self):
diff --git a/Modules/datetimemodule.c b/Modules/datetimemodule.c
index d39791a8e84..488d062998a 100644
--- a/Modules/datetimemodule.c
+++ b/Modules/datetimemodule.c
@@ -4027,7 +4027,7 @@ datetime_str(PyDateTime_DateTime *self)
 static PyObject *
 datetime_isoformat(PyDateTime_DateTime *self, PyObject *args, PyObject *kw)
 {
-	char sep = 'T';
+	int sep = 'T';
 	static char *keywords[] = {"sep", NULL};
 	char buffer[100];
 	PyObject *result;
diff --git a/Python/getargs.c b/Python/getargs.c
index 7b2738834a3..1730bff1fff 100644
--- a/Python/getargs.c
+++ b/Python/getargs.c
@@ -761,15 +761,14 @@ convertsimple(PyObject *arg, const char **p_format, va_list *p_va, int flags,
 #endif /* WITHOUT_COMPLEX */
 	
 	case 'c': {/* char */
-		char *p = va_arg(*p_va, char *);
+		int *p = va_arg(*p_va, int *);
 		if (PyString_Check(arg) && PyString_Size(arg) == 1)
 			*p = PyString_AS_STRING(arg)[0];
 		else if (PyUnicode_Check(arg) &&
-			 PyUnicode_GET_SIZE(arg) == 1 &&
-			 PyUnicode_AS_UNICODE(arg)[0] < 256)
+			 PyUnicode_GET_SIZE(arg) == 1)
 			*p = PyUnicode_AS_UNICODE(arg)[0];
 		else
-			return converterr("char < 256", arg, msgbuf, bufsize);
+			return converterr("char", arg, msgbuf, bufsize);
 		break;
 	}
 	
diff --git a/Python/modsupport.c b/Python/modsupport.c
index 781a331493b..ba464099dd5 100644
--- a/Python/modsupport.c
+++ b/Python/modsupport.c
@@ -385,9 +385,22 @@ do_mkvalue(const char **p_format, va_list *p_va, int flags)
 
 		case 'c':
 		{
-			char p[1];
-			p[0] = (char)va_arg(*p_va, int);
-			return PyString_FromStringAndSize(p, 1);
+			int i = va_arg(*p_va, int);
+			Py_UNICODE c;
+			if (i < 0 || i > PyUnicode_GetMax()) {
+#ifdef Py_UNICODE_WIDE
+				PyErr_SetString(PyExc_OverflowError,
+				                "%c arg not in range(0x110000) "
+				                "(wide Python build)");
+#else
+				PyErr_SetString(PyExc_OverflowError,
+				                "%c arg not in range(0x10000) "
+				                "(narrow Python build)");
+#endif
+				return NULL;
+			}
+			c = i;
+			return PyUnicode_FromUnicode(&c, 1);
 		}
 
 		case 's':