diff --git a/fwdpy11/headers/fwdpy11/genetic_values/fwdpp_wrappers/fwdpp_genetic_value.hpp b/fwdpy11/headers/fwdpy11/genetic_values/fwdpp_wrappers/fwdpp_genetic_value.hpp
index fde032eaa9..80ae930083 100644
--- a/fwdpy11/headers/fwdpy11/genetic_values/fwdpp_wrappers/fwdpp_genetic_value.hpp
+++ b/fwdpy11/headers/fwdpy11/genetic_values/fwdpp_wrappers/fwdpp_genetic_value.hpp
@@ -4,7 +4,7 @@
 #include <type_traits>
 #include <functional>
 #include "../DiploidGeneticValue.hpp"
-#include <fwdpp/fitness_models.hpp>
+#include <fwdpy11/genetic_values/site_dependent_fitness.hpp>
 #include <fwdpy11/genetic_value_noise/GeneticValueNoise.hpp>
 
 namespace fwdpy11
@@ -26,7 +26,7 @@ namespace fwdpy11
             }
 
             inline double
-            operator()(const fwdpp::site_dependent_genetic_value& gv,
+            operator()(const fwdpy11::site_dependent_genetic_value& gv,
                        const std::size_t diploid_index,
                        const DiploidMetadata& /*metadata*/,
                        const DiploidPopulation& pop) const
@@ -47,7 +47,7 @@ namespace fwdpy11
             }
 
             inline double
-            operator()(const fwdpp::site_dependent_genetic_value& gv,
+            operator()(const fwdpy11::site_dependent_genetic_value& gv,
                        const std::size_t diploid_index, const DiploidMetadata& metadata,
                        const DiploidPopulation& pop) const
             {
@@ -75,7 +75,7 @@ namespace fwdpy11
         };
 
         using callback_type = std::function<double(
-            const fwdpp::site_dependent_genetic_value&, const std::size_t,
+            const fwdpy11::site_dependent_genetic_value&, const std::size_t,
             const DiploidMetadata&, const DiploidPopulation&)>;
 
         using make_return_value_t = std::function<double(double)>;
@@ -90,7 +90,7 @@ namespace fwdpy11
             return multi_deme_callback(aa_scaling);
         }
 
-        fwdpp::site_dependent_genetic_value gv;
+        fwdpy11::site_dependent_genetic_value gv;
         double aa_scaling;
         make_return_value_t make_return_value;
         callback_type callback;
diff --git a/fwdpy11/headers/fwdpy11/genetic_values/site_dependent_fitness.hpp b/fwdpy11/headers/fwdpy11/genetic_values/site_dependent_fitness.hpp
new file mode 100644
index 0000000000..8c609a7415
--- /dev/null
+++ b/fwdpy11/headers/fwdpy11/genetic_values/site_dependent_fitness.hpp
@@ -0,0 +1,218 @@
+#pragma once
+
+#include <fwdpp/type_traits.hpp>
+
+namespace fwdpy11
+{
+    struct site_dependent_genetic_value
+    {
+        //! The return value type
+        using result_type = double;
+
+        template <typename iterator_t, typename MutationContainerType,
+                  typename updating_policy_hom, typename updating_policy_het,
+                  typename make_return_value>
+        inline result_type
+        operator()(iterator_t first1, iterator_t last1, iterator_t first2,
+                   iterator_t last2, const MutationContainerType &mutations,
+                   const updating_policy_hom &fpol_hom,
+                   const updating_policy_het &fpol_het,
+                   const make_return_value &rv_function,
+                   const double starting_value) const noexcept
+        /*!
+          Range-based call operator.  Calculates genetic values over ranges of
+          mutation keys first1/last1
+          and first2/last2, which are iterators derived from the 'smutations'
+          of two haploid_genomes in a diploid.
+
+          \param first1 Iterator to first mutation derived from haploid_genome 1
+          \param last1 Iterator to one past the last mutation derived from
+          haploid_genome 1
+          \param first2 Iterator to first mutation derived from haploid_genome 2
+          \param last2 Iterator to one past the last mutation derived from
+          haploid_genome 2
+          \param mutations The container of mutations for the simulation
+          \param fpol_hom Policy that updates genetic value for a homozygous
+          mutation.
+          \param fpol_het Policy that updates genetic value for a heterozygous
+          mutation.
+          \param make_return_value Policy generated the final return value.
+                 Must be equivalent to std::function<double(double)>
+          \param starting_value The initial genetic value.
+
+          \returns Fitness (double)
+        */
+        {
+            static_assert(fwdpp::traits::is_mutation<
+                              typename MutationContainerType::value_type>::value,
+                          "MutationContainerType::value_type must be a mutation type");
+            static_assert(
+                std::is_convertible<
+                    updating_policy_hom,
+                    std::function<void(double &, const typename MutationContainerType::
+                                                     value_type &)>>::value,
+                "decltype(fpol_hom) must be convertible to "
+                "std::function<void(double &,const typename "
+                "MutationContainerType::value_type");
+            static_assert(
+                std::is_convertible<
+                    updating_policy_het,
+                    std::function<void(double &, const typename MutationContainerType::
+                                                     value_type &)>>::value,
+                "decltype(fpol_het) must be convertible to "
+                "std::function<void(double &,const typename "
+                "MutationContainerType::value_type");
+            result_type w = starting_value;
+            if (first1 == last1 && first2 == last2)
+                return rv_function(w);
+            else if (first1 == last1)
+                {
+                    for (; first2 != last2; ++first2)
+                        fpol_het(w, mutations[*first2]);
+                    return rv_function(w);
+                }
+            else if (first2 == last2)
+                {
+                    for (; first1 != last1; ++first1)
+                        fpol_het(w, mutations[*first1]);
+                    return rv_function(w);
+                }
+            for (; first1 != last1; ++first1)
+                {
+                    for (; first2 != last2 && *first1 != *first2
+                           && mutations[*first2].pos < mutations[*first1].pos;
+                         ++first2)
+                        // All mutations in this range are Aa
+                        {
+                            fpol_het(w, mutations[*first2]);
+                        }
+                    if (first2 < last2
+                        && (*first1 == *first2
+                            || mutations[*first1].pos == mutations[*first2].pos))
+                        // mutation with index first1 is homozygous
+                        {
+                            fpol_hom(w, mutations[*first1]);
+                            ++first2; // increment so that we don't re-process
+                            // this site as a het next time 'round
+                        }
+                    else // mutation first1 is heterozygous
+                        {
+                            fpol_het(w, mutations[*first1]);
+                        }
+                }
+            for (; first2 != last2; ++first2)
+                {
+                    fpol_het(w, mutations[*first2]);
+                }
+            return rv_function(w);
+        }
+
+        template <typename iterator_t, typename MutationContainerType,
+                  typename updating_policy_hom, typename updating_policy_het>
+        inline result_type
+        operator()(iterator_t first1, iterator_t last1, iterator_t first2,
+                   iterator_t last2, const MutationContainerType &mutations,
+                   const updating_policy_hom &fpol_hom,
+                   const updating_policy_het &fpol_het,
+                   const double starting_value) const noexcept
+        {
+            return this->operator()(
+                first1, last1, first2, last2, mutations, fpol_hom, fpol_het,
+                [](double d) { return d; }, starting_value);
+        }
+
+        template <typename HaploidGenomeType, typename MutationContainerType,
+                  typename updating_policy_hom, typename updating_policy_het,
+                  typename make_return_value>
+        inline result_type
+        operator()(const HaploidGenomeType &g1, const HaploidGenomeType &g2,
+                   const MutationContainerType &mutations,
+                   const updating_policy_hom &fpol_hom,
+                   const updating_policy_het &fpol_het,
+                   const make_return_value &rv_function,
+                   const double starting_value) const noexcept
+        /*!
+          Calculates genetic value for a diploid whose genotype
+          across sites is given by haploid_genomes g1 and  g2.
+
+          \param g1 A haploid_genome
+          \param g2 A haploid_genome
+          \param mutations The container of mutations for the simulation
+          \param fpol_hom Policy that updates genetic value for a homozygous
+          mutation.
+          \param fpol_het Policy that updates genetic value for a heterozygous
+          mutation.
+          \param starting_value The initial genetic value.
+
+          \returns Fitness (double)
+        */
+        {
+            static_assert(fwdpp::traits::is_haploid_genome<HaploidGenomeType>::value,
+                          "HaploidGenomeType::value_type must be a haploid_genome "
+                          "type");
+            return this->operator()(g1.smutations.cbegin(), g1.smutations.cend(),
+                                    g2.smutations.cbegin(), g2.smutations.cend(),
+                                    mutations, fpol_hom, fpol_het, rv_function,
+                                    starting_value);
+        }
+
+        template <typename HaploidGenomeType, typename MutationContainerType,
+                  typename updating_policy_hom, typename updating_policy_het>
+        inline result_type
+        operator()(const HaploidGenomeType &g1, const HaploidGenomeType &g2,
+                   const MutationContainerType &mutations,
+                   const updating_policy_hom &fpol_hom,
+                   const updating_policy_het &fpol_het,
+                   const double starting_value) const noexcept
+        {
+            return this->operator()(
+                g1, g2, mutations, fpol_hom, fpol_het, [](double d) { return d; },
+                starting_value);
+        }
+
+        template <typename DiploidType, typename GenomeContainerType,
+                  typename MutationContainerType, typename updating_policy_hom,
+                  typename updating_policy_het, typename make_return_value>
+        inline result_type
+        operator()(const DiploidType &dip, const GenomeContainerType &haploid_genomes,
+                   const MutationContainerType &mutations,
+                   const updating_policy_hom &fpol_hom,
+                   const updating_policy_het &fpol_het,
+                   const make_return_value &rv_function,
+                   const double starting_value) const noexcept
+        /*!
+          Calculates genetic value for a diploid type.
+
+          \param dip A diploid
+          \param haploid_genomes The container of haploid_genomes for the simulation.
+          \param mutations The container of mutations for the simulation
+          \param fpol_hom Policy that updates genetic value for a homozygous
+          mutation.
+          \param fpol_het Policy that updates genetic value for a heterozygous
+          mutation.
+          \param starting_value The initial genetic value.
+
+          \returns Fitness (double)
+        */
+        {
+            return this->operator()(haploid_genomes[dip.first],
+                                    haploid_genomes[dip.second], mutations, fpol_hom,
+                                    fpol_het, rv_function, starting_value);
+        }
+
+        template <typename DiploidType, typename GenomeContainerType,
+                  typename MutationContainerType, typename updating_policy_hom,
+                  typename updating_policy_het>
+        inline result_type
+        operator()(const DiploidType &dip, const GenomeContainerType &haploid_genomes,
+                   const MutationContainerType &mutations,
+                   const updating_policy_hom &fpol_hom,
+                   const updating_policy_het &fpol_het,
+                   const double starting_value) const noexcept
+        {
+            return this->operator()(
+                dip, haploid_genomes, mutations, fpol_hom, fpol_het,
+                [](double d) { return d; }, starting_value);
+        }
+    };
+}