diff --git a/include/boost/smart_ptr/allocate_unique.hpp b/include/boost/smart_ptr/allocate_unique.hpp
index ca84050..3cb7ef0 100644
--- a/include/boost/smart_ptr/allocate_unique.hpp
+++ b/include/boost/smart_ptr/allocate_unique.hpp
@@ -89,11 +89,9 @@ public:
         return boost::to_address(p_);
     }
 
-#if !defined(BOOST_NO_CXX11_EXPLICIT_CONVERSION_OPERATORS)
     explicit operator bool() const BOOST_SP_NOEXCEPT {
         return !!p_;
     }
-#endif
 
     bool operator!() const BOOST_SP_NOEXCEPT {
         return !p_;
@@ -138,11 +136,9 @@ public:
         return p_[i];
     }
 
-#if !defined(BOOST_NO_CXX11_EXPLICIT_CONVERSION_OPERATORS)
     explicit operator bool() const BOOST_SP_NOEXCEPT {
         return !!p_;
     }
-#endif
 
     bool operator!() const BOOST_SP_NOEXCEPT {
         return !p_;
@@ -187,11 +183,9 @@ public:
         return p_[i];
     }
 
-#if !defined(BOOST_NO_CXX11_EXPLICIT_CONVERSION_OPERATORS)
     explicit operator bool() const BOOST_SP_NOEXCEPT {
         return !!p_;
     }
-#endif
 
     bool operator!() const BOOST_SP_NOEXCEPT {
         return !p_;
diff --git a/include/boost/smart_ptr/detail/operator_bool.hpp b/include/boost/smart_ptr/detail/operator_bool.hpp
index f9c5ef6..dca171b 100644
--- a/include/boost/smart_ptr/detail/operator_bool.hpp
+++ b/include/boost/smart_ptr/detail/operator_bool.hpp
@@ -6,57 +6,11 @@
 //  See accompanying file LICENSE_1_0.txt or copy at
 //  http://www.boost.org/LICENSE_1_0.txt
 
-#if !defined( BOOST_NO_CXX11_EXPLICIT_CONVERSION_OPERATORS ) && !defined( BOOST_NO_CXX11_NULLPTR )\
-    && !(defined(__SUNPRO_CC) && BOOST_WORKAROUND(__SUNPRO_CC, <= 0x5130))
-
     explicit operator bool () const BOOST_SP_NOEXCEPT
     {
         return px != 0;
     }
 
-#elif ( defined(__SUNPRO_CC) && BOOST_WORKAROUND(__SUNPRO_CC, < 0x570) ) || defined(__CINT__)
-
-    operator bool () const BOOST_SP_NOEXCEPT
-    {
-        return px != 0;
-    }
-
-#elif defined( _MANAGED )
-
-    static void unspecified_bool( this_type*** )
-    {
-    }
-
-    typedef void (*unspecified_bool_type)( this_type*** );
-
-    operator unspecified_bool_type() const BOOST_SP_NOEXCEPT
-    {
-        return px == 0? 0: unspecified_bool;
-    }
-
-#elif \
-    ( defined(__MWERKS__) && BOOST_WORKAROUND(__MWERKS__, < 0x3200) ) || \
-    ( defined(__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ < 304) ) || \
-    ( defined(__SUNPRO_CC) && BOOST_WORKAROUND(__SUNPRO_CC, <= 0x590) )
-
-    typedef element_type * (this_type::*unspecified_bool_type)() const;
-
-    operator unspecified_bool_type() const BOOST_SP_NOEXCEPT
-    {
-        return px == 0? 0: &this_type::get;
-    }
-
-#else
-
-    typedef element_type * this_type::*unspecified_bool_type;
-
-    operator unspecified_bool_type() const BOOST_SP_NOEXCEPT
-    {
-        return px == 0? 0: &this_type::px;
-    }
-
-#endif
-
     // operator! is redundant, but some compilers need it
     bool operator! () const BOOST_SP_NOEXCEPT
     {