Minor typo
diff --git a/docs/advanced/functions.rst b/docs/advanced/functions.rst
index e3acff0..4d28f06 100644
--- a/docs/advanced/functions.rst
+++ b/docs/advanced/functions.rst
@@ -438,7 +438,7 @@
py::class_<Cat>(m, "Cat").def(py::init<>());
m.def("bark", [](Dog *dog) -> std::string {
if (dog) return "woof!"; /* Called with a Dog instance */
- else return "(no dog)"; /* Called with None, d == nullptr */
+ else return "(no dog)"; /* Called with None, dog == nullptr */
}, py::arg("dog").none(true));
m.def("meow", [](Cat *cat) -> std::string {
// Can't be called with None argument