diff --git a/include/boost/multiprecision/gmp.hpp b/include/boost/multiprecision/gmp.hpp
index 3aaada75..c0390c06 100644
--- a/include/boost/multiprecision/gmp.hpp
+++ b/include/boost/multiprecision/gmp.hpp
@@ -1510,13 +1510,15 @@ protected:
 
 inline mp_number<gmp_int> numerator(const mp_number<gmp_rational>& val)
 {
-   const __mpz_struct* pz = (mpq_numref(val.backend().data()));
-   return mp_number<gmp_int>((mpz_t&)pz);
+   mp_number<gmp_int> result;
+   mpz_set(result.backend().data(), (mpq_numref(val.backend().data())));
+   return result;
 }
 inline mp_number<gmp_int> denominator(const mp_number<gmp_rational>& val)
 {
-   const __mpz_struct* pz = mpq_denref(val.backend().data());
-   return mp_number<gmp_int>((mpz_t&)pz);
+   mp_number<gmp_int> result;
+   mpz_set(result.backend().data(), (mpq_denref(val.backend().data())));
+   return result;
 }
 
 inline void add(gmp_rational& t, const gmp_rational& o)
diff --git a/include/boost/multiprecision/mpfr.hpp b/include/boost/multiprecision/mpfr.hpp
index bf478e42..47b20140 100644
--- a/include/boost/multiprecision/mpfr.hpp
+++ b/include/boost/multiprecision/mpfr.hpp
@@ -7,6 +7,7 @@
 #define BOOST_MATH_BN_MPFR_HPP
 
 #include <boost/multiprecision/mp_number.hpp>
+#include <boost/multiprecision/gmp.hpp>
 #include <boost/math/special_functions/fpclassify.hpp>
 #include <boost/cstdint.hpp>
 #include <boost/lexical_cast.hpp>
@@ -244,6 +245,48 @@ struct mpfr_float_backend : public detail::mpfr_float_imp<digits10>
 #ifndef BOOST_NO_RVALUE_REFERENCES
    mpfr_float_backend(mpfr_float_backend&& o) : detail::mpfr_float_imp<digits10>(o) {}
 #endif
+   template <unsigned D>
+   mpfr_float_backend(const mpfr_float_backend<D>& val)
+   {
+      mpfr_init2(this->m_data, ((digits10 + 1) * 1000L) / 301L);
+      mpfr_set(this->m_data, val.data(), GMP_RNDN);
+   }
+   template <unsigned D>
+   mpfr_float_backend(const gmp_float<D>& val)
+   {
+      mpfr_init2(this->m_data, ((digits10 + 1) * 1000L) / 301L);
+      mpfr_set_f(this->m_data, val.data(), GMP_RNDN);
+   }
+   mpfr_float_backend(const gmp_int& val)
+   {
+      mpfr_init2(this->m_data, ((digits10 + 1) * 1000L) / 301L);
+      mpfr_set_z(this->m_data, val.data(), GMP_RNDN);
+   }
+   mpfr_float_backend(const gmp_rational& val)
+   {
+      mpfr_init2(this->m_data, ((digits10 + 1) * 1000L) / 301L);
+      mpfr_set_q(this->m_data, val.data(), GMP_RNDN);
+   }
+   mpfr_float_backend(mpfr_t val)
+   {
+      mpfr_init2(this->m_data, ((digits10 + 1) * 1000L) / 301L);
+      mpfr_set(this->m_data, val, GMP_RNDN);
+   }
+   mpfr_float_backend(mpf_t val)
+   {
+      mpfr_init2(this->m_data, ((digits10 + 1) * 1000L) / 301L);
+      mpfr_set_f(this->m_data, val, GMP_RNDN);
+   }
+   mpfr_float_backend(mpz_t val)
+   {
+      mpfr_init2(this->m_data, ((digits10 + 1) * 1000L) / 301L);
+      mpfr_set_z(this->m_data, val, GMP_RNDN);
+   }
+   mpfr_float_backend(mpq_t val)
+   {
+      mpfr_init2(this->m_data, ((digits10 + 1) * 1000L) / 301L);
+      mpfr_set_q(this->m_data, val, GMP_RNDN);
+   }
    mpfr_float_backend& operator=(const mpfr_float_backend& o)
    {
       *static_cast<detail::mpfr_float_imp<digits10>*>(this) = static_cast<detail::mpfr_float_imp<digits10> const&>(o);
@@ -262,6 +305,48 @@ struct mpfr_float_backend : public detail::mpfr_float_imp<digits10>
       *static_cast<detail::mpfr_float_imp<digits10>*>(this) = v;
       return *this;
    }
+   mpfr_float_backend& operator=(const mpfr_t& val)
+   {
+      mpfr_set(this->m_data, val, GMP_RNDN);
+      return *this;
+   }
+   mpfr_float_backend& operator=(const mpf_t& val)
+   {
+      mpfr_set_f(this->m_data, val, GMP_RNDN);
+      return *this;
+   }
+   mpfr_float_backend& operator=(const mpz_t& val)
+   {
+      mpfr_set_z(this->m_data, val, GMP_RNDN);
+      return *this;
+   }
+   mpfr_float_backend& operator=(const mpq_t& val)
+   {
+      mpfr_set_q(this->m_data, val, GMP_RNDN);
+      return *this;
+   }
+   template <unsigned D>
+   mpfr_float_backend& operator=(const mpfr_float_backend<D>& val)
+   {
+      mpfr_set(this->m_data, val.data(), GMP_RNDN);
+      return *this;
+   }
+   template <unsigned D>
+   mpfr_float_backend& operator=(const gmp_float<D>& val)
+   {
+      mpfr_set_f(this->m_data, val.data(), GMP_RNDN);
+      return *this;
+   }
+   mpfr_float_backend& operator=(const gmp_int& val)
+   {
+      mpfr_set_z(this->m_data, val.data(), GMP_RNDN);
+      return *this;
+   }
+   mpfr_float_backend& operator=(const gmp_rational& val)
+   {
+      mpfr_set_q(this->m_data, val.data(), GMP_RNDN);
+      return *this;
+   }
 };
 
 template <>
@@ -275,6 +360,26 @@ struct mpfr_float_backend<0> : public detail::mpfr_float_imp<0>
    {
       mpfr_init2(this->m_data, ((digits10 + 1) * 1000L) / 301L);
    }
+   mpfr_float_backend(mpfr_t val)
+   {
+      mpfr_init2(this->m_data, ((get_default_precision() + 1) * 1000L) / 301L);
+      mpfr_set(this->m_data, val, GMP_RNDN);
+   }
+   mpfr_float_backend(mpf_t val)
+   {
+      mpfr_init2(this->m_data, ((get_default_precision() + 1) * 1000L) / 301L);
+      mpfr_set_f(this->m_data, val, GMP_RNDN);
+   }
+   mpfr_float_backend(mpz_t val)
+   {
+      mpfr_init2(this->m_data, ((get_default_precision() + 1) * 1000L) / 301L);
+      mpfr_set_z(this->m_data, val, GMP_RNDN);
+   }
+   mpfr_float_backend(mpq_t val)
+   {
+      mpfr_init2(this->m_data, ((get_default_precision() + 1) * 1000L) / 301L);
+      mpfr_set_q(this->m_data, val, GMP_RNDN);
+   }
    mpfr_float_backend(const mpfr_float_backend& o) : detail::mpfr_float_imp<0>(o) {}
 #ifndef BOOST_NO_RVALUE_REFERENCES
    mpfr_float_backend(mpfr_float_backend&& o) : detail::mpfr_float_imp<0>(o) {}
@@ -284,6 +389,28 @@ struct mpfr_float_backend<0> : public detail::mpfr_float_imp<0>
       mpfr_init2(this->m_data, ((digits10 + 1) * 1000L) / 301L);
       *this = o;
    }
+   template <unsigned D>
+   mpfr_float_backend(const mpfr_float_backend<D>& val)
+   {
+      mpfr_init2(this->m_data, ((get_default_precision() + 1) * 1000L) / 301L);
+      mpfr_set(this->m_data, val.data(), GMP_RNDN);
+   }
+   template <unsigned D>
+   mpfr_float_backend(const gmp_float<D>& val)
+   {
+      mpfr_init2(this->m_data, ((digits10 + 1) * 1000L) / 301L);
+      mpfr_set_f(this->m_data, val.data(), GMP_RNDN);
+   }
+   mpfr_float_backend(const gmp_int& val)
+   {
+      mpfr_init2(this->m_data, ((get_default_precision() + 1) * 1000L) / 301L);
+      mpfr_set_z(this->m_data, val.data(), GMP_RNDN);
+   }
+   mpfr_float_backend(const gmp_rational& val)
+   {
+      mpfr_init2(this->m_data, ((get_default_precision() + 1) * 1000L) / 301L);
+      mpfr_set_q(this->m_data, val.data(), GMP_RNDN);
+   }
 
    mpfr_float_backend& operator=(const mpfr_float_backend& o)
    {
@@ -303,6 +430,48 @@ struct mpfr_float_backend<0> : public detail::mpfr_float_imp<0>
       *static_cast<detail::mpfr_float_imp<0>*>(this) = v;
       return *this;
    }
+   mpfr_float_backend& operator=(const mpfr_t& val)
+   {
+      mpfr_set(this->m_data, val, GMP_RNDN);
+      return *this;
+   }
+   mpfr_float_backend& operator=(const mpf_t& val)
+   {
+      mpfr_set_f(this->m_data, val, GMP_RNDN);
+      return *this;
+   }
+   mpfr_float_backend& operator=(const mpz_t& val)
+   {
+      mpfr_set_z(this->m_data, val, GMP_RNDN);
+      return *this;
+   }
+   mpfr_float_backend& operator=(const mpq_t& val)
+   {
+      mpfr_set_q(this->m_data, val, GMP_RNDN);
+      return *this;
+   }
+   template <unsigned D>
+   mpfr_float_backend& operator=(const mpfr_float_backend<D>& val)
+   {
+      mpfr_set(this->m_data, val.data(), GMP_RNDN);
+      return *this;
+   }
+   template <unsigned D>
+   mpfr_float_backend& operator=(const gmp_float<D>& val)
+   {
+      mpfr_set_f(this->m_data, val.data(), GMP_RNDN);
+      return *this;
+   }
+   mpfr_float_backend& operator=(const gmp_int& val)
+   {
+      mpfr_set_z(this->m_data, val.data(), GMP_RNDN);
+      return *this;
+   }
+   mpfr_float_backend& operator=(const gmp_rational& val)
+   {
+      mpfr_set_q(this->m_data, val.data(), GMP_RNDN);
+      return *this;
+   }
    static unsigned default_precision()
    {
       return get_default_precision();