diff --git a/include/boost/enable_shared_from_this.hpp b/include/boost/enable_shared_from_this.hpp
index d3f8ab8..affed6f 100644
--- a/include/boost/enable_shared_from_this.hpp
+++ b/include/boost/enable_shared_from_this.hpp
@@ -60,7 +60,7 @@ public:
     }
 
     typedef T _internal_element_type; // for bcc 5.5.1
-    weak_ptr<_internal_element_type> _internal_weak_this;
+    mutable weak_ptr<_internal_element_type> _internal_weak_this;
 };
 
 } // namespace boost
diff --git a/include/boost/shared_ptr.hpp b/include/boost/shared_ptr.hpp
index d4b44e6..a5e4adf 100644
--- a/include/boost/shared_ptr.hpp
+++ b/include/boost/shared_ptr.hpp
@@ -83,9 +83,9 @@ template<> struct shared_ptr_traits<void const volatile>
 
 // enable_shared_from_this support
 
-template<class T, class Y> void sp_enable_shared_from_this(boost::enable_shared_from_this<T> * pe, Y * px, shared_count const & pn)
+template<class T, class Y> void sp_enable_shared_from_this(boost::enable_shared_from_this<T> const * pe, Y const * px, shared_count const & pn)
 {
-    if(pe != 0) pe->_internal_weak_this._internal_assign(px, pn);
+    if(pe != 0) pe->_internal_weak_this._internal_assign(const_cast<Y*>(px), pn);
 }
 
 inline void sp_enable_shared_from_this(void const volatile *, void const volatile *, shared_count const &)