diff --git a/include/boost/python/converter/pyobject_type.hpp b/include/boost/python/converter/pyobject_type.hpp
index 526f9f9d..bde39e80 100644
--- a/include/boost/python/converter/pyobject_type.hpp
+++ b/include/boost/python/converter/pyobject_type.hpp
@@ -9,8 +9,11 @@
 
 namespace boost { namespace python { namespace converter { 
 
-BOOST_PYTHON_DECL PyObject* checked_downcast_impl(PyObject*, PyTypeObject*);
-
+BOOST_PYTHON_DECL inline
+PyObject* checked_downcast_impl(PyObject *obj, PyTypeObject *type)
+{
+  return (PyType_IsSubtype(Py_TYPE(obj), type) ? obj : NULL);
+}
 // Used as a base class for specializations which need to provide
 // Python type checking capability.
 template <class Object, PyTypeObject* pytype>
diff --git a/include/boost/python/numpy/dtype.hpp b/include/boost/python/numpy/dtype.hpp
index 9633d37d..b9e95f9b 100644
--- a/include/boost/python/numpy/dtype.hpp
+++ b/include/boost/python/numpy/dtype.hpp
@@ -56,7 +56,7 @@ public:
    *  This is more permissive than equality tests.  For instance, if long and int are the same
    *  size, the dtypes corresponding to each will be equivalent, but not equal.
    */
-  friend bool equivalent(dtype const & a, dtype const & b);
+  friend BOOST_NUMPY_DECL bool equivalent(dtype const & a, dtype const & b);
 
   /**
    *  @brief Register from-Python converters for NumPy's built-in array scalar types.