diff --git a/examples/shared_ptr_modify_in_place.cpp b/examples/shared_ptr_modify_in_place.cpp
index b61f14d8..d4eb82af 100644
--- a/examples/shared_ptr_modify_in_place.cpp
+++ b/examples/shared_ptr_modify_in_place.cpp
@@ -15,21 +15,21 @@ int main() {
 
 	sol::state lua;
 
-	auto new_shared_ptr = [](sol::stack_object obj) {
+	auto new_shared_ptr = [](sol::stack_reference obj) {
 		// works just fine
 		sol::stack::modify_unique_usertype(obj, [](std::shared_ptr<ree>& sptr) {
 			sptr = std::make_shared<ree>(sptr->value + 1);
 		});
 	};
 
-	auto reset_shared_ptr = [](sol::stack_object obj) {
+	auto reset_shared_ptr = [](sol::stack_reference obj) {
 		sol::stack::modify_unique_usertype(obj, [](std::shared_ptr<ree>& sptr) {
 			// THIS IS SUCH A BAD IDEA AAAGH
 			sptr.reset();
 			// DO NOT reset to nullptr:
 			// change it to an actual NEW value...
 			// otherwise you will inject a nullptr into the userdata representation...
-			// which will NOT compare == to nil
+			// which will NOT compare == to Lua's nil
 		});
 	};
 
diff --git a/sol/stack_core.hpp b/sol/stack_core.hpp
index 1b81fa44..7632f82c 100644
--- a/sol/stack_core.hpp
+++ b/sol/stack_core.hpp
@@ -872,7 +872,7 @@ namespace sol {
 		}
 
 		template <typename T, typename F>
-		inline void modify_unique_usertype_as(stack_object obj, F&& f) {
+		inline void modify_unique_usertype_as(const stack_reference& obj, F&& f) {
 			typedef unique_usertype_traits<T> u_traits;
 			void* raw = lua_touserdata(obj.lua_state(), obj.stack_index());
 			void* ptr_memory = detail::align_usertype_pointer(raw);
@@ -883,7 +883,7 @@ namespace sol {
 		}
 
 		template <typename F>
-		inline void modify_unique_usertype(stack_object obj, F&& f) {
+		inline void modify_unique_usertype(const stack_reference& obj, F&& f) {
 			typedef meta::bind_traits<meta::unqualified_t<F>> bt;
 			typedef typename bt::template arg_at<0> T;
 			modify_unique_usertype_as<meta::unqualified_t<T>>(obj, std::forward<F>(f));