diff --git a/Optional b/Optional
index 45112c08..70ad9085 160000
--- a/Optional
+++ b/Optional
@@ -1 +1 @@
-Subproject commit 45112c085a4ca75b5591dde3bf46faf4969c3026
+Subproject commit 70ad908553b0bbac144452ce0dcc98d6dfe565a4
diff --git a/single/sol/sol.hpp b/single/sol/sol.hpp
index 5f6f10a4..9e01bf1d 100644
--- a/single/sol/sol.hpp
+++ b/single/sol/sol.hpp
@@ -20,8 +20,8 @@
 // CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 // This file was generated with a script.
-// Generated 2016-09-04 15:42:29.271382 UTC
-// This header was generated with sol v2.12.2 (revision cb0116a)
+// Generated 2016-09-11 00:47:45.107316 UTC
+// This header was generated with sol v2.12.3 (revision edb8eac)
 // https://github.com/ThePhD/sol2
 
 #ifndef SOL_SINGLE_INCLUDE_HPP
@@ -1442,10 +1442,10 @@ public:
     return ref != nullptr;
   }
   
-  template <class V>
-  constexpr typename ::std::decay<T>::type value_or(V&& v) const
+  template <typename V>
+  constexpr T& value_or(V&& v) const
   {
-    return *this ? **this : detail_::convert<typename ::std::decay<T>::type>(constexpr_forward<V>(v));
+    return *this ? **this : detail_::convert<T&>(constexpr_forward<V>(v));
   }
 };
 
@@ -9382,7 +9382,7 @@ namespace sol {
 	namespace usertype_detail {
 		struct no_comp {
 			template <typename A, typename B>
-			bool operator()(A&&, B&&) {
+			bool operator()(A&&, B&&) const {
 				return false;
 			}
 		};
diff --git a/sol/usertype_metatable.hpp b/sol/usertype_metatable.hpp
index c29e0082..a41131f7 100644
--- a/sol/usertype_metatable.hpp
+++ b/sol/usertype_metatable.hpp
@@ -37,7 +37,7 @@ namespace sol {
 	namespace usertype_detail {
 		struct no_comp {
 			template <typename A, typename B>
-			bool operator()(A&&, B&&) {
+			bool operator()(A&&, B&&) const {
 				return false;
 			}
 		};
diff --git a/test_usertypes.cpp b/test_usertypes.cpp
index 16413e01..d6736388 100644
--- a/test_usertypes.cpp
+++ b/test_usertypes.cpp
@@ -72,6 +72,18 @@ public:
 	}
 };
 
+class abstract_A {
+public:
+	virtual void a() = 0;
+};
+
+class abstract_B : public abstract_A {
+public:
+	virtual void a() override {
+		INFO("overridden a() in B : public A - BARK");
+	}
+};
+
 struct Vec {
 	float x, y, z;
 	Vec(float x, float y, float z) : x{ x }, y{ y }, z{ z } {}
@@ -1405,3 +1417,13 @@ TEST_CASE("usertype/unique_usertype-check", "make sure unique usertypes don't ge
 	my_func(std::make_shared<Entity>());
 	});
 }
+
+TEST_CASE("usertype/abstract-base-class", "Ensure that abstract base classes and such can be registered") {
+	
+	sol::state lua;
+	lua.new_usertype<abstract_A>("A", "a", &abstract_A::a);
+	lua.new_usertype<abstract_B>("B", sol::base_classes, sol::bases<abstract_A>());
+	lua.script(R"(local b = B.new()
+b:a()
+)");
+}