diff --git a/albatross/core/parameter_handling_mixin.h b/albatross/core/parameter_handling_mixin.h
index 6903bf2a..d009e828 100644
--- a/albatross/core/parameter_handling_mixin.h
+++ b/albatross/core/parameter_handling_mixin.h
@@ -39,7 +39,7 @@ struct Parameter {
   ParameterPrior prior;
 
   Parameter() : value(), prior(nullptr){};
-  Parameter(ParameterValue value_) : value(value_) {}
+  Parameter(ParameterValue value_) : value(value_), prior(nullptr) {}
   Parameter(ParameterValue value_, const ParameterPrior &prior_)
       : value(value_), prior(prior_){};
   /*
@@ -162,7 +162,14 @@ class ParameterHandlingMixin {
     }
   }
 
-  void set_param(const ParameterKey &key, const ParameterValue &value) {
+  void set_param_values(const std::map<ParameterKey, ParameterValue> &values) {
+    for (const auto &pair : values) {
+      check_param_key(pair.first);
+      unchecked_set_param(pair.first, pair.second);
+    }
+  }
+
+  void set_param_value(const ParameterKey &key, const ParameterValue &value) {
     check_param_key(key);
     unchecked_set_param(key, value);
   }
@@ -172,6 +179,14 @@ class ParameterHandlingMixin {
     unchecked_set_param(key, param);
   }
 
+  // This just avoids the situation where a user would call `set_param`
+  // with a double, which may then be viewed by the compiler as the
+  // initialization argument for a `Parameter` which would then
+  // inadvertently overwrite the prior.
+  void set_param(const ParameterKey &key, const ParameterValue &value) {
+    set_param_value(key, value);
+  }
+
   void set_prior(const ParameterKey &key, const ParameterPrior &prior) {
     check_param_key(key);
     unchecked_set_prior(key, prior);
@@ -242,17 +257,17 @@ class ParameterHandlingMixin {
     }
   }
 
-  ParameterValue get_param_value(const std::string &name) const {
+  ParameterValue get_param_value(const ParameterKey &name) const {
     return get_params().at(name).value;
   }
 
-  void unchecked_set_param(const std::string &name,
+  void unchecked_set_param(const ParameterKey &name,
                            const ParameterValue value) {
     Parameter param = {value, get_params()[name].prior};
     unchecked_set_param(name, param);
   }
 
-  void unchecked_set_prior(const std::string &name,
+  void unchecked_set_prior(const ParameterKey &name,
                            const ParameterPrior &prior) {
     Parameter param = {get_params()[name].value, prior};
     unchecked_set_param(name, param);
@@ -281,7 +296,7 @@ class ParameterHandlingMixin {
 
   virtual ParameterStore get_params() const { return params_; }
 
-  virtual void unchecked_set_param(const std::string &name,
+  virtual void unchecked_set_param(const ParameterKey &name,
                                    const Parameter &param) {
     params_[name] = param;
   }
diff --git a/albatross/covariance_functions/covariance_functions.h b/albatross/covariance_functions/covariance_functions.h
index a794b6e1..2cf50d44 100644
--- a/albatross/covariance_functions/covariance_functions.h
+++ b/albatross/covariance_functions/covariance_functions.h
@@ -74,8 +74,13 @@ template <typename Term> struct CovarianceFunction {
   inline auto set_params(const ParameterStore &params) {
     return term.set_params(params);
   };
-  inline auto set_param(const ParameterKey &key, const ParameterValue &value) {
-    return term.set_param(key, value);
+  inline auto
+  set_param_values(const std::map<ParameterKey, ParameterValue> &values) {
+    return term.set_param_values(values);
+  };
+  inline auto set_param_value(const ParameterKey &key,
+                              const ParameterValue &value) {
+    return term.set_param_value(key, value);
   };
   inline auto set_param(const ParameterKey &key, const Parameter &param) {
     return term.set_param(key, param);
diff --git a/albatross/covariance_functions/covariance_term.h b/albatross/covariance_functions/covariance_term.h
index 910387e8..b52ccb2e 100644
--- a/albatross/covariance_functions/covariance_term.h
+++ b/albatross/covariance_functions/covariance_term.h
@@ -71,7 +71,7 @@ class CombinationOfCovarianceTerms : public CovarianceTerm {
     return map_join(lhs_.get_params(), rhs_.get_params());
   }
 
-  void unchecked_set_param(const std::string &name,
+  void unchecked_set_param(const ParameterKey &name,
                            const Parameter &param) override {
     if (map_contains(lhs_.get_params(), name)) {
       lhs_.set_param(name, param);
diff --git a/albatross/covariance_functions/scaling_function.h b/albatross/covariance_functions/scaling_function.h
index cb9cf214..adb45ce6 100644
--- a/albatross/covariance_functions/scaling_function.h
+++ b/albatross/covariance_functions/scaling_function.h
@@ -78,6 +78,10 @@ template <typename ScalingFunction> class ScalingTerm : public CovarianceTerm {
     scaling_function_.set_params(params);
   }
 
+  void set_param_values(const std::map<ParameterKey, ParameterValue> &values) {
+    scaling_function_.set_param_values(values);
+  }
+
   virtual ParameterStore get_params() const override {
     return scaling_function_.get_params();
   }
@@ -94,7 +98,7 @@ template <typename ScalingFunction> class ScalingTerm : public CovarianceTerm {
     archive(cereal::make_nvp("scaling_function", scaling_function_));
   }
 
-  void unchecked_set_param(const std::string &name,
+  void unchecked_set_param(const ParameterKey &name,
                            const Parameter &param) override {
     scaling_function_.set_param(name, param);
   }
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index dcd1103a..401eb054 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -5,19 +5,21 @@ set(CMAKE_CXX_FLAGS "-Wshadow -Wswitch-default -Wswitch-enum -Wundef -Wuninitial
 
 add_executable(albatross_unit_tests
 EXCLUDE_FROM_ALL
+test_core_distribution.cc
 test_core_model.cc
 test_covariance_functions.cc
 test_distance_metrics.cc
 test_evaluate.cc
 test_map_utils.cc
-test_serialize.cc
-test_parameter_handling_mixin.cc
+test_model_adapter.cc
 test_models.cc
-test_core_distribution.cc
+test_parameter_handling_mixin.cc
+test_radial.cc
+test_scaling_function.cc
+test_serializable_ldlt.cc
+test_serialize.cc
 test_tune.cc
 test_tuning_metrics.cc
-test_serializable_ldlt.cc
-test_radial.cc
 )
 
 add_dependencies(albatross_unit_tests
diff --git a/tests/test_model_adapter.cc b/tests/test_model_adapter.cc
index 8276fd6b..d15aea77 100644
--- a/tests/test_model_adapter.cc
+++ b/tests/test_model_adapter.cc
@@ -31,9 +31,9 @@ class TestAdaptedModel : public TestAdaptedModelBase {
 
   std::string get_name() const override { return "test_adapted"; };
 
-  const Eigen::VectorXd convert_feature(const double &x) const {
+  const Eigen::VectorXd convert_feature(const double &x) const override {
     Eigen::VectorXd converted(2);
-    converted << 1., (x - this->params_.at("center"));
+    converted << 1., (x - this->get_param_value("center"));
     return converted;
   }
 
@@ -59,7 +59,7 @@ void test_get_set(albatross::RegressionModel<double> &model,
                   const std::string &key) {
   // Make sure a key exists, then modify it and make sure it
   // takes on the new value.
-  const auto orig = model.get_params().at(key);
+  const auto orig = model.get_param_value(key);
   model.set_param(key, orig + 1.);
   EXPECT_EQ(model.get_params().at(key), orig + 1.);
 }
diff --git a/tests/test_parameter_handling_mixin.cc b/tests/test_parameter_handling_mixin.cc
index 8b46b97f..f99eaee8 100644
--- a/tests/test_parameter_handling_mixin.cc
+++ b/tests/test_parameter_handling_mixin.cc
@@ -127,4 +127,26 @@ TEST(test_parameter_handler, test_set_prior) {
   }
 };
 
+TEST(test_parameter_handler, test_set_param_values_doesnt_overwrite_prior) {
+  auto p = TestParameterHandler();
+
+  const auto orig_params = p.get_params();
+
+  std::map<std::string, double> new_params;
+  for (const auto &pair : orig_params) {
+    new_params[pair.first] = pair.second.value + 1.;
+  }
+
+  p.set_param_values(new_params);
+
+  for (const auto &pair : orig_params) {
+    // Make sure we changed the parameter value
+    const auto new_param = p.get_params().at(pair.first);
+    EXPECT_NE(new_param.value, pair.second.value);
+    // but not the prior.
+    EXPECT_TRUE(!pair.second.has_prior() ||
+                (pair.second.prior == new_param.prior));
+  }
+};
+
 } // namespace albatross
diff --git a/tests/test_scaling_function.cc b/tests/test_scaling_function.cc
index 6592793d..02fa65c2 100644
--- a/tests/test_scaling_function.cc
+++ b/tests/test_scaling_function.cc
@@ -111,8 +111,8 @@ TEST(test_scaling_functions, test_predicts) {
   auto model = gp_from_covariance<double>(covariance_function);
 
   auto folds = leave_one_out(dataset);
-  auto cv_scores =
-      cross_validated_scores(root_mean_square_error, folds, &model);
+  auto cv_scores = cross_validated_scores(
+      evaluation_metrics::root_mean_square_error, folds, &model);
 
   EXPECT_LE(cv_scores.mean(), 0.01);
 }