diff --git a/result_of_test.cpp b/result_of_test.cpp
index cea59ee..5dd3df6 100644
--- a/result_of_test.cpp
+++ b/result_of_test.cpp
@@ -3,14 +3,14 @@
 #include <boost/static_assert.hpp>
 #include <boost/type_traits/is_same.hpp>
 
-class int_result_type { typedef int result_type; };
+struct int_result_type { typedef int result_type; };
 
-class int_result_of
+struct int_result_of
 {
   template<typename F> struct result { typedef int type; };
 };
 
-class int_result_type_and_float_result_of
+struct int_result_type_and_float_result_of
 {
   typedef int result_type;
   template<typename F> struct result { typedef float type; };
@@ -23,13 +23,23 @@ int main()
   using namespace boost;
 
   typedef int (*func_ptr)(float, double);
+  typedef int (&func_ref)(float, double);
   typedef int (X::*mem_func_ptr)(float);
+  typedef int (X::*mem_func_ptr_c)(float) const;
+  typedef int (X::*mem_func_ptr_v)(float) volatile;
+  typedef int (X::*mem_func_ptr_cv)(float) const volatile;
 
   BOOST_STATIC_ASSERT((is_same<result_of<int_result_type(float)>::type, int>::value));
   BOOST_STATIC_ASSERT((is_same<result_of<int_result_of(double)>::type, int>::value));
   BOOST_STATIC_ASSERT((is_same<result_of<int_result_of(void)>::type, void>::value));
+  BOOST_STATIC_ASSERT((is_same<result_of<const int_result_of(double)>::type, int>::value));
+  BOOST_STATIC_ASSERT((is_same<result_of<volatile int_result_of(void)>::type, void>::value));
   BOOST_STATIC_ASSERT((is_same<result_of<int_result_type_and_float_result_of(char)>::type, int>::value));
   BOOST_STATIC_ASSERT((is_same<result_of<func_ptr(char, float)>::type, int>::value));
+  BOOST_STATIC_ASSERT((is_same<result_of<func_ref(char, float)>::type, int>::value));
   BOOST_STATIC_ASSERT((is_same<result_of<mem_func_ptr(X,char)>::type, int>::value));
+  BOOST_STATIC_ASSERT((is_same<result_of<mem_func_ptr_c(X,char)>::type, int>::value));
+  BOOST_STATIC_ASSERT((is_same<result_of<mem_func_ptr_v(X,char)>::type, int>::value));
+  BOOST_STATIC_ASSERT((is_same<result_of<mem_func_ptr_cv(X,char)>::type, int>::value));
   return 0;
 }