diff --git a/include/boost/type_traits/is_polymorphic.hpp b/include/boost/type_traits/is_polymorphic.hpp
index 37542a8..c9bb14d 100644
--- a/include/boost/type_traits/is_polymorphic.hpp
+++ b/include/boost/type_traits/is_polymorphic.hpp
@@ -10,6 +10,7 @@
 #include <boost/type_traits/remove_cv.hpp>
 // should be the last #include
 #include "boost/type_traits/detail/bool_trait_def.hpp"
+#include <boost/detail/workaround.hpp>
 
 namespace boost{
 namespace detail{
@@ -17,25 +18,29 @@ namespace detail{
 template <class T>
 struct is_polymorphic_imp1
 {
+# if BOOST_WORKAROUND(__MWERKS__, <= 0x2407) // CWPro7 should return false always.
+    typedef char d1, (&d2)[2];
+# else 
    typedef typename remove_cv<T>::type ncvT;
    struct d1 : public ncvT
    {
       d1();
-# if !defined(__GNUC__) // this raises warnings with some classes, and buys nothing with GCC
+#  if !defined(__GNUC__) // this raises warnings with some classes, and buys nothing with GCC
       ~d1()throw();
-# endif 
+#  endif 
       char padding[256];
    };
    struct d2 : public ncvT
    {
       d2();
       virtual ~d2()throw();
-#ifndef BOOST_MSVC
+#  ifndef BOOST_MSVC
       // for some reason this messes up VC++ when T has virtual bases:
       virtual void foo();
-#endif
+#  endif
       char padding[256];
    };
+# endif 
    BOOST_STATIC_CONSTANT(bool, value = (sizeof(d2) == sizeof(d1)));
 };