diff --git a/cpptests/test_fixation_pruning_during_simulation.cc b/cpptests/test_fixation_pruning_during_simulation.cc
index 2ce37003a..f8fee82d9 100644
--- a/cpptests/test_fixation_pruning_during_simulation.cc
+++ b/cpptests/test_fixation_pruning_during_simulation.cc
@@ -36,9 +36,9 @@ strong_positive_selection()
     auto sweights = std::vector<double>(1.);
     std::vector<std::unique_ptr<fwdpy11::Sregion>> nregions, sregions;
 
-    sregions.emplace_back(fwdpy11::ExpS(fwdpy11::Region(0., 10., 1.0, true, 0),
-                                                2.0, 0.025, fwdpy11::fixed_dominance(1.))
-                                      .clone());
+    sregions.emplace_back(fwdpy11::ExpS(fwdpy11::Region(0., 10., 1.0, true, 0), 2.0,
+                                        0.025, fwdpy11::fixed_dominance(1.))
+                              .clone());
     return fwdpy11::MutationRegions::create(0., nweights, sweights, nregions, sregions);
 }
 
@@ -87,10 +87,35 @@ BOOST_AUTO_TEST_SUITE(test_remove_fixations_multiplicative)
 
 BOOST_FIXTURE_TEST_CASE(test_remove_fixations, common_setup)
 {
-    const auto sample_recorder_callback
-        = [](const fwdpy11::DiploidPopulation &, fwdpy11::SampleRecorder &) {
-
-          };
+    const auto sample_recorder_callback = [](const fwdpy11::DiploidPopulation &pop,
+                                             fwdpy11::SampleRecorder &) {
+        for (const auto diploid : pop.diploids)
+            {
+                for (const auto m : pop.haploid_genomes[diploid.first].smutations)
+                    {
+                        if (pop.mcounts[m] == 2 * pop.N)
+                            {
+                                for (std::size_t i = 0; i < pop.fixations.size(); ++i)
+                                    {
+                                        if (pop.fixations[i].g == pop.mutations[m].g
+                                            && pop.fixations[i].pos
+                                                   == pop.mutations[m].pos
+                                            && pop.fixations[i].s == pop.mutations[m].s)
+                                            {
+                                                if (pop.fixation_times[i]
+                                                    != pop.generation)
+                                                    {
+                                                        throw std::runtime_error(
+                                                            "fixation found in genome "
+                                                            "that did not occur this "
+                                                            "generation");
+                                                    }
+                                            }
+                                    }
+                            }
+                    }
+            }
+    };
     BOOST_REQUIRE_EQUAL(mregions.weights.size(), mregions.regions.size());
     BOOST_REQUIRE_EQUAL(mregions.weights.size(), 1);
     options.track_mutation_counts_during_sim = true;