Fix a refleak
diff --git a/Modules/itertoolsmodule.c b/Modules/itertoolsmodule.c
index 61128d2..a8063c5 100644
--- a/Modules/itertoolsmodule.c
+++ b/Modules/itertoolsmodule.c
@@ -2133,7 +2133,7 @@
 	if (robj != Py_None) {
 		if (!PyLong_Check(robj)) {
 			PyErr_SetString(PyExc_TypeError, "Expected int as r");
-			return NULL;
+			goto error;
 		}
 		r = PyLong_AsSsize_t(robj);
 		if (r == -1 && PyErr_Occurred())