diff --git a/Python/getargs.c b/Python/getargs.c
index ac85a6d..f11649a 100644
--- a/Python/getargs.c
+++ b/Python/getargs.c
@@ -665,11 +665,14 @@
 	case 'n': /* Py_ssize_t */
 #if SIZEOF_SIZE_T != SIZEOF_LONG
 	{
+		PyObject *iobj;
 		Py_ssize_t *p = va_arg(*p_va, Py_ssize_t *);
-		Py_ssize_t ival;
+		Py_ssize_t ival = -1;
 		if (float_argument_error(arg))
 			return converterr("integer<n>", arg, msgbuf, bufsize);
-		ival = PyNumber_AsSsize_t(arg);
+		iobj = PyNumber_Index(arg);
+		if (iobj != NULL)
+			ival = PyNumber_AsSsize_t(arg);
 		if (ival == -1 && PyErr_Occurred())
 			return converterr("integer<n>", arg, msgbuf, bufsize);
 		*p = ival;