diff --git a/extras/test.cpp b/extras/test.cpp
index 89cfd7f..39fa88c 100644
--- a/extras/test.cpp
+++ b/extras/test.cpp
@@ -10,5 +10,15 @@
 #include <list>
 #include <vector>
 
+namespace stdcpp::test {
+    template<typename T>
+    std::size_t cppSizeOf() {
+        return sizeof(T);
+    }
+};
+
 template class std::list<int>;
+template std::size_t stdcpp::test::cppSizeOf<std::list<int> >();
+
 template class std::vector<int>;
+template std::size_t stdcpp::test::cppSizeOf<std::vector<int> >();
diff --git a/source/stdcpp/test/base.d b/source/stdcpp/test/base.d
new file mode 100644
index 0000000..4b2bc02
--- /dev/null
+++ b/source/stdcpp/test/base.d
@@ -0,0 +1,12 @@
+/*******************************************************************************
+
+    Utilities to be used in tests
+
+*******************************************************************************/
+
+module stdcpp.test.base;
+
+version (unittest):
+
+/// Returns: the `sizeof` of `T` as seen by the C++ compiler
+extern(C++, "stdcpp", "test") size_t cppSizeOf (T) ();
diff --git a/source/stdcpp/test/list.d b/source/stdcpp/test/list.d
index 9de7608..aef2f0a 100644
--- a/source/stdcpp/test/list.d
+++ b/source/stdcpp/test/list.d
@@ -6,15 +6,17 @@
 
 module stdcpp.test.list;
 
+import stdcpp.test.base;
 import stdcpp.list;
 
+/// Test that the sizes matches
 unittest
 {
-    version (CppRuntime_Microsoft)
-        static assert(list!int.sizeof == 16);
-    else
-        static assert(list!int.sizeof == 24);
+    assert(cppSizeOf!(list!int) == list!int.sizeof);
+}
 
+unittest
+{
     auto p = list!int(5);
     p.push_back(5);
     assert(p.size() == 6);
diff --git a/source/stdcpp/test/vector.d b/source/stdcpp/test/vector.d
index 74b85b9..2302eaf 100644
--- a/source/stdcpp/test/vector.d
+++ b/source/stdcpp/test/vector.d
@@ -6,7 +6,15 @@
 
 module stdcpp.test.vector;
 
+import stdcpp.test.base;
 import stdcpp.vector;
+
+/// Test that the sizes matches
+unittest
+{
+    assert(cppSizeOf!(vector!int) == vector!int.sizeof);
+}
+
 version (CppRuntime_Gcc)
 {
     unittest
@@ -39,7 +47,6 @@ version (CppRuntime_Gcc)
         assert(p.capacity() == 12);
         p.resize(5);
         assert(p.length == 5);
-        assert(p.sizeof == 24);//verifying three pointers
         p.assign(3,8);
         assert(p.length == 3);
         p.push_back(4);
@@ -82,7 +89,6 @@ else version (CppRuntime_Clang)
         assert(vec.empty == 0);
         vec.reserve(6);
         assert(vec.capacity == 6);
-        assert(vec.sizeof == 24);
         vec.assign(3,8);
         assert(vec.length == 3);
         assert(vec[0] == 8);
@@ -98,8 +104,5 @@ else version (CppRuntime_Clang)
         vec3.swap(vec);
         assert(vec3.size == 9); // after swap
         assert(vec.size == 7);
-
-
-
     }
 }