diff --git a/include/boost/multiprecision/cpp_int.hpp b/include/boost/multiprecision/cpp_int.hpp
index 20e77d77..23d91973 100644
--- a/include/boost/multiprecision/cpp_int.hpp
+++ b/include/boost/multiprecision/cpp_int.hpp
@@ -2811,7 +2811,7 @@ inline Integer negate_integer(Integer i, const mpl::true_&) BOOST_NOEXCEPT
 template <class Integer>
 inline Integer negate_integer(Integer i, const mpl::false_&) BOOST_NOEXCEPT
 {
-   return ~--i;
+   return ~(i-1);
 }
 
 template <class R, unsigned MinBits, bool Signed, class Allocator>
diff --git a/include/boost/multiprecision/detail/number_base.hpp b/include/boost/multiprecision/detail/number_base.hpp
index 0d7fe45a..ab3e34fe 100644
--- a/include/boost/multiprecision/detail/number_base.hpp
+++ b/include/boost/multiprecision/detail/number_base.hpp
@@ -78,6 +78,16 @@ struct canonical_imp
 {
    typedef typename remove_cv<typename decay<const Val>::type>::type type;
 };
+template <class B, class Backend, class Tag>
+struct canonical_imp<number<B, true>, Backend, Tag>
+{
+   typedef B type;
+};
+template <class B, class Backend, class Tag>
+struct canonical_imp<number<B, false>, Backend, Tag>
+{
+   typedef B type;
+};
 template <class Val, class Backend>
 struct canonical_imp<Val, Backend, mpl::int_<0> >
 {
diff --git a/include/boost/multiprecision/number.hpp b/include/boost/multiprecision/number.hpp
index 55b38314..b30e7891 100644
--- a/include/boost/multiprecision/number.hpp
+++ b/include/boost/multiprecision/number.hpp
@@ -112,7 +112,7 @@ public:
    explicit BOOST_FORCEINLINE number(const number<Other, ET>& val, typename enable_if_c<
          (detail::is_explicitly_convertible<Other, Backend>::value 
             && (detail::is_restricted_conversion<Other, Backend>::value || !boost::is_convertible<Other, Backend>::value))
-         >::type* = 0) BOOST_NOEXCEPT_IF(noexcept(std::declval<Backend>() = std::declval<Other>()))
+         >::type* = 0) BOOST_NOEXCEPT_IF(noexcept(Backend(std::declval<Other>())))
       : m_backend(val.backend()) {}
 
    template <class V>
@@ -148,13 +148,13 @@ public:
       do_assign(e, tag_type());
       return *this;
    }
-/*
+
    BOOST_FORCEINLINE number& operator=(const number& e) BOOST_NOEXCEPT_IF(noexcept(std::declval<Backend>() = static_cast<const Backend&>(std::declval<Backend>())))
    {
       m_backend = e.m_backend;
       return *this;
    }
-   */
+
    template <class V>
    BOOST_FORCEINLINE typename enable_if<is_convertible<V, self_type>, number<Backend, ExpressionTemplates>& >::type 
       operator=(const V& v) BOOST_NOEXCEPT_IF(noexcept(std::declval<Backend>() = std::declval<typename boost::multiprecision::detail::canonical<V, Backend>::type>()))
@@ -603,6 +603,11 @@ explicit operator T()const
 {
    return this->template convert_to<T>();
 }
+explicit operator bool()const
+{
+   using default_ops::eval_is_zero;
+   return !eval_is_zero(backend());
+}
 #endif
    //
    // Default precision:
diff --git a/test/test_arithmetic.cpp b/test/test_arithmetic.cpp
index 99c1bb8b..4a6f102f 100644
--- a/test/test_arithmetic.cpp
+++ b/test/test_arithmetic.cpp
@@ -485,16 +485,16 @@ void test_integer_ops(const boost::mpl::int_<boost::multiprecision::number_kind_
    Real r;
    divide_qr(a, b, c, r);
    BOOST_TEST(c == a / b);
-   BOOST_TEST(r = a % b);
+   BOOST_TEST(r == a % b);
    divide_qr(a + 0, b, c, r);
    BOOST_TEST(c == a / b);
-   BOOST_TEST(r = a % b);
+   BOOST_TEST(r == a % b);
    divide_qr(a, b+0, c, r);
    BOOST_TEST(c == a / b);
-   BOOST_TEST(r = a % b);
+   BOOST_TEST(r == a % b);
    divide_qr(a+0, b+0, c, r);
    BOOST_TEST(c == a / b);
-   BOOST_TEST(r = a % b);
+   BOOST_TEST(r == a % b);
    BOOST_TEST(integer_modulus(a, 57) == a % 57);
    if(std::numeric_limits<Real>::is_signed)
    {
@@ -516,17 +516,17 @@ void test_integer_ops(const boost::mpl::int_<boost::multiprecision::number_kind_
       BOOST_TEST(lcm(-400, b) == boost::math::lcm(-400, 45));
       divide_qr(a, b, c, r);
       BOOST_TEST(c == a / b);
-      BOOST_TEST(r = a % b);
+      BOOST_TEST(r == a % b);
       BOOST_TEST(integer_modulus(a, 57) == abs(a % 57));
       b = -57;
       divide_qr(a, b, c, r);
       BOOST_TEST(c == a / b);
-      BOOST_TEST(r = a % b);
+      BOOST_TEST(r == a % b);
       BOOST_TEST(integer_modulus(a, -57) == abs(a % -57));
       a = 458;
       divide_qr(a, b, c, r);
       BOOST_TEST(c == a / b);
-      BOOST_TEST(r = a % b);
+      BOOST_TEST(r == a % b);
       BOOST_TEST(integer_modulus(a, -57) == abs(a % -57));
    }
    for(unsigned i = 0; i < 20; ++i)