diff --git a/cpptests/test_site_dependent_genetic_value.cc b/cpptests/test_site_dependent_genetic_value.cc
index a7ca3514e..5d0e76ef8 100644
--- a/cpptests/test_site_dependent_genetic_value.cc
+++ b/cpptests/test_site_dependent_genetic_value.cc
@@ -201,7 +201,7 @@ BOOST_FIXTURE_TEST_CASE(test_multiplicative_fitness_1, Fwdpy11Pop)
     BOOST_REQUIRE(offspring_metadata[0].w > 0.0);
 
     // we now pass in this correct lambda expression
-    m = fwdpy11::multiplicative_fitness_model(1, 2., nullptr, nullptr);
+    m = fwdpy11::multiplicative_fitness_model(1, 2., nullptr);
     m(data);
     BOOST_REQUIRE_EQUAL(offspring_metadata[0].g, 0.);
     BOOST_REQUIRE_EQUAL(offspring_metadata[0].w, 0.);
diff --git a/fwdpy11/headers/fwdpy11/genetic_values/DiploidAdditive.hpp b/fwdpy11/headers/fwdpy11/genetic_values/DiploidAdditive.hpp
index 3ca418212..134a44859 100644
--- a/fwdpy11/headers/fwdpy11/genetic_values/DiploidAdditive.hpp
+++ b/fwdpy11/headers/fwdpy11/genetic_values/DiploidAdditive.hpp
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <fwdpy11/types/Mutation.hpp>
+#include <fwdpy11/genetic_value_to_fitness/GeneticValueIsTrait.hpp>
 #include "fwdpp_wrappers/fwdpp_genetic_value.hpp"
 
 namespace fwdpy11
@@ -73,4 +74,23 @@ namespace fwdpy11
         single_deme_additive_het, single_deme_additive_hom, multi_deme_additive_het,
         multi_deme_additive_hom, 0>;
 
+    inline DiploidAdditive
+    additive_fitness_model(std::size_t ndemes, double scaling,
+                           const GeneticValueNoise* noise)
+    {
+        return DiploidAdditive(
+            ndemes, scaling, final_additive_fitness(),
+            [](const double) { return false; }, nullptr, noise);
+    }
+
+    inline DiploidAdditive
+    additive_trait_model(std::size_t ndemes, double scaling,
+                         const GeneticValueIsTrait* gvalue_to_fitness,
+                         const GeneticValueNoise* noise)
+    {
+        return DiploidAdditive(
+            ndemes, scaling, final_additive_trait(), [](const double) { return false; },
+            gvalue_to_fitness, noise);
+    }
+
 }
diff --git a/fwdpy11/headers/fwdpy11/genetic_values/DiploidMultiplicative.hpp b/fwdpy11/headers/fwdpy11/genetic_values/DiploidMultiplicative.hpp
index 27bae186f..c0bb4416f 100644
--- a/fwdpy11/headers/fwdpy11/genetic_values/DiploidMultiplicative.hpp
+++ b/fwdpy11/headers/fwdpy11/genetic_values/DiploidMultiplicative.hpp
@@ -77,12 +77,11 @@ namespace fwdpy11
 
     inline DiploidMultiplicative
     multiplicative_fitness_model(std::size_t ndemes, double scaling,
-                                 const GeneticValueIsTrait* gvalue_to_fitness,
                                  const GeneticValueNoise* noise)
     {
         return DiploidMultiplicative(
             ndemes, scaling, final_multiplicative_fitness(),
-            [](const double w) { return w <= 0.0; }, gvalue_to_fitness, noise);
+            [](const double w) { return w <= 0.0; }, nullptr, noise);
     }
 
     inline DiploidMultiplicative