diff --git a/include/boost/detail/shared_array_nmt.hpp b/include/boost/detail/shared_array_nmt.hpp
index e5137a3..570af13 100644
--- a/include/boost/detail/shared_array_nmt.hpp
+++ b/include/boost/detail/shared_array_nmt.hpp
@@ -72,6 +72,7 @@ public:
       
     void reset(T * p = 0)
     {
+        BOOST_ASSERT(p == 0 || p != px);
         shared_array(p).swap(*this);
     }
       
diff --git a/include/boost/detail/shared_ptr_nmt.hpp b/include/boost/detail/shared_ptr_nmt.hpp
index 8b268a2..5364e77 100644
--- a/include/boost/detail/shared_ptr_nmt.hpp
+++ b/include/boost/detail/shared_ptr_nmt.hpp
@@ -91,6 +91,7 @@ public:
 
     void reset(T * p = 0)
     {
+        BOOST_ASSERT(p == 0 || p != px);
         shared_ptr(p).swap(*this);
     }
 
diff --git a/include/boost/shared_array.hpp b/include/boost/shared_array.hpp
index 85741b2..5098dee 100644
--- a/include/boost/shared_array.hpp
+++ b/include/boost/shared_array.hpp
@@ -71,6 +71,7 @@ public:
 
     void reset(T * p = 0)
     {
+        BOOST_ASSERT(p == 0 || p != px);
         this_type(p).swap(*this);
     }
 
diff --git a/include/boost/shared_ptr.hpp b/include/boost/shared_ptr.hpp
index 996a1b5..db75b9e 100644
--- a/include/boost/shared_ptr.hpp
+++ b/include/boost/shared_ptr.hpp
@@ -33,7 +33,7 @@
 #ifdef BOOST_MSVC  // moved here to work around VC++ compiler crash
 # pragma warning(push)
 # pragma warning(disable:4284) // odd return type for operator->
-#endif    
+#endif
 
 namespace boost
 {
@@ -144,9 +144,15 @@ public:
 
     void reset(T * p = 0)
     {
+        BOOST_ASSERT(p == 0 || p != px);
         this_type(p).swap(*this);
     }
 
+    template<typename D> void reset(T * p, D d)
+    {
+        this_type(p, d).swap(*this);
+    }
+
     typename detail::shared_ptr_traits<T>::reference operator* () const // never throws
     {
         BOOST_ASSERT(px != 0);