diff --git a/src/lib/libkrbn/src/libkrbn_configuration.cpp b/src/lib/libkrbn/src/libkrbn_configuration.cpp
index fe5d8ac95..aff85a81d 100644
--- a/src/lib/libkrbn/src/libkrbn_configuration.cpp
+++ b/src/lib/libkrbn/src/libkrbn_configuration.cpp
@@ -17,23 +17,25 @@ gsl::not_null<std::shared_ptr<krbn::core_configuration::core_configuration>> get
   return empty_core_configuration;
 }
 
-krbn::core_configuration::details::simple_modifications* find_simple_modifications(const libkrbn_device_identifiers* device_identifiers) {
+gsl::not_null<std::shared_ptr<krbn::core_configuration::details::simple_modifications>> find_simple_modifications(const libkrbn_device_identifiers* device_identifiers) {
   auto di = libkrbn_cpp::make_device_identifiers(device_identifiers);
   auto c = get_current_core_configuration();
   if (di.empty()) {
-    return &(c->get_selected_profile().get_simple_modifications());
+    return c->get_selected_profile().get_simple_modifications();
   } else {
-    return c->get_selected_profile().find_simple_modifications(di);
+    auto d = c->get_selected_profile().get_device(di);
+    return d->get_simple_modifications();
   }
 }
 
-krbn::core_configuration::details::simple_modifications* find_fn_function_keys(const libkrbn_device_identifiers* device_identifiers) {
+gsl::not_null<std::shared_ptr<krbn::core_configuration::details::simple_modifications>> find_fn_function_keys(const libkrbn_device_identifiers* device_identifiers) {
   auto di = libkrbn_cpp::make_device_identifiers(device_identifiers);
   auto c = get_current_core_configuration();
   if (di.empty()) {
-    return &(c->get_selected_profile().get_fn_function_keys());
+    return c->get_selected_profile().get_fn_function_keys();
   } else {
-    return c->get_selected_profile().find_fn_function_keys(di);
+    auto d = c->get_selected_profile().get_device(di);
+    return d->get_fn_function_keys();
   }
 }
 } // namespace
@@ -222,10 +224,8 @@ void libkrbn_core_configuration_set_selected_profile_parameters_delay_millisecon
 }
 
 size_t libkrbn_core_configuration_get_selected_profile_simple_modifications_size(const libkrbn_device_identifiers* device_identifiers) {
-  if (auto m = find_simple_modifications(device_identifiers)) {
-    return m->get_pairs().size();
-  }
-  return 0;
+  auto m = find_simple_modifications(device_identifiers);
+  return m->get_pairs().size();
 }
 
 bool libkrbn_core_configuration_get_selected_profile_simple_modification_from_json_string(size_t index,
@@ -236,12 +236,11 @@ bool libkrbn_core_configuration_get_selected_profile_simple_modification_from_js
     buffer[0] = '\0';
   }
 
-  if (auto m = find_simple_modifications(device_identifiers)) {
-    const auto& pairs = m->get_pairs();
-    if (index < pairs.size()) {
-      strlcpy(buffer, pairs[index].first.c_str(), length);
-      return true;
-    }
+  auto m = find_simple_modifications(device_identifiers);
+  const auto& pairs = m->get_pairs();
+  if (index < pairs.size()) {
+    strlcpy(buffer, pairs[index].first.c_str(), length);
+    return true;
   }
 
   return false;
@@ -255,13 +254,13 @@ bool libkrbn_core_configuration_get_selected_profile_simple_modification_to_json
     buffer[0] = '\0';
   }
 
-  if (auto m = find_simple_modifications(device_identifiers)) {
-    const auto& pairs = m->get_pairs();
-    if (index < pairs.size()) {
-      strlcpy(buffer, pairs[index].second.c_str(), length);
-      return true;
-    }
+  auto m = find_simple_modifications(device_identifiers);
+  const auto& pairs = m->get_pairs();
+  if (index < pairs.size()) {
+    strlcpy(buffer, pairs[index].second.c_str(), length);
+    return true;
   }
+
   return false;
 }
 
@@ -269,32 +268,27 @@ void libkrbn_core_configuration_replace_selected_profile_simple_modification(siz
                                                                              const char* from_json_string,
                                                                              const char* to_json_string,
                                                                              const libkrbn_device_identifiers* device_identifiers) {
-  if (auto m = find_simple_modifications(device_identifiers)) {
-    if (from_json_string &&
-        to_json_string) {
-      m->replace_pair(index, from_json_string, to_json_string);
-    }
+  auto m = find_simple_modifications(device_identifiers);
+  if (from_json_string &&
+      to_json_string) {
+    m->replace_pair(index, from_json_string, to_json_string);
   }
 }
 
 void libkrbn_core_configuration_push_back_selected_profile_simple_modification(const libkrbn_device_identifiers* device_identifiers) {
-  if (auto m = find_simple_modifications(device_identifiers)) {
-    m->push_back_pair();
-  }
+  auto m = find_simple_modifications(device_identifiers);
+  m->push_back_pair();
 }
 
 void libkrbn_core_configuration_erase_selected_profile_simple_modification(size_t index,
                                                                            const libkrbn_device_identifiers* device_identifiers) {
-  if (auto m = find_simple_modifications(device_identifiers)) {
-    m->erase_pair(index);
-  }
+  auto m = find_simple_modifications(device_identifiers);
+  m->erase_pair(index);
 }
 
 size_t libkrbn_core_configuration_get_selected_profile_fn_function_keys_size(const libkrbn_device_identifiers* device_identifiers) {
-  if (auto k = find_fn_function_keys(device_identifiers)) {
-    return k->get_pairs().size();
-  }
-  return 0;
+  auto k = find_fn_function_keys(device_identifiers);
+  return k->get_pairs().size();
 }
 
 bool libkrbn_core_configuration_get_selected_profile_fn_function_key_from_json_string(size_t index,
@@ -305,12 +299,11 @@ bool libkrbn_core_configuration_get_selected_profile_fn_function_key_from_json_s
     buffer[0] = '\0';
   }
 
-  if (auto k = find_fn_function_keys(device_identifiers)) {
-    const auto& pairs = k->get_pairs();
-    if (index < pairs.size()) {
-      strlcpy(buffer, pairs[index].first.c_str(), length);
-      return true;
-    }
+  auto k = find_fn_function_keys(device_identifiers);
+  const auto& pairs = k->get_pairs();
+  if (index < pairs.size()) {
+    strlcpy(buffer, pairs[index].first.c_str(), length);
+    return true;
   }
 
   return false;
@@ -324,12 +317,11 @@ bool libkrbn_core_configuration_get_selected_profile_fn_function_key_to_json_str
     buffer[0] = '\0';
   }
 
-  if (auto k = find_fn_function_keys(device_identifiers)) {
-    const auto& pairs = k->get_pairs();
-    if (index < pairs.size()) {
-      strlcpy(buffer, pairs[index].second.c_str(), length);
-      return true;
-    }
+  auto k = find_fn_function_keys(device_identifiers);
+  const auto& pairs = k->get_pairs();
+  if (index < pairs.size()) {
+    strlcpy(buffer, pairs[index].second.c_str(), length);
+    return true;
   }
 
   return false;
@@ -338,11 +330,10 @@ bool libkrbn_core_configuration_get_selected_profile_fn_function_key_to_json_str
 void libkrbn_core_configuration_replace_selected_profile_fn_function_key(const char* from_json_string,
                                                                          const char* to_json_string,
                                                                          const libkrbn_device_identifiers* device_identifiers) {
-  if (auto k = find_fn_function_keys(device_identifiers)) {
-    if (from_json_string &&
-        to_json_string) {
-      k->replace_second(from_json_string, to_json_string);
-    }
+  auto k = find_fn_function_keys(device_identifiers);
+  if (from_json_string &&
+      to_json_string) {
+    k->replace_second(from_json_string, to_json_string);
   }
 }
 
diff --git a/src/share/core_configuration/details/profile.hpp b/src/share/core_configuration/details/profile.hpp
index b0024df86..999c6b42f 100644
--- a/src/share/core_configuration/details/profile.hpp
+++ b/src/share/core_configuration/details/profile.hpp
@@ -19,7 +19,9 @@ class profile final {
           error_handling error_handling)
       : json_(json),
         error_handling_(error_handling),
-        selected_(false) {
+        selected_(false),
+        simple_modifications_(std::make_shared<simple_modifications>()),
+        fn_function_keys_(std::make_shared<simple_modifications>()) {
     helper_values_.push_back_array<details::device>("devices",
                                                     devices_);
 
@@ -27,7 +29,7 @@ class profile final {
     // Set default value
     //
 
-    fn_function_keys_.update(make_default_fn_function_keys_json());
+    fn_function_keys_->update(make_default_fn_function_keys_json());
 
     //
     // Load from json
@@ -57,14 +59,14 @@ class profile final {
 
       } else if (key == "simple_modifications") {
         try {
-          simple_modifications_.update(value);
+          simple_modifications_->update(value);
         } catch (const pqrs::json::unmarshal_error& e) {
           throw pqrs::json::unmarshal_error(fmt::format("`{0}` error: {1}", key, e.what()));
         }
 
       } else if (key == "fn_function_keys") {
         try {
-          fn_function_keys_.update(value);
+          fn_function_keys_->update(value);
         } catch (const pqrs::json::unmarshal_error& e) {
           throw pqrs::json::unmarshal_error(fmt::format("`{0}` error: {1}", key, e.what()));
         }
@@ -148,8 +150,8 @@ class profile final {
     j["name"] = name_;
     j["selected"] = selected_;
     j["parameters"] = parameters_;
-    j["simple_modifications"] = simple_modifications_.to_json(nlohmann::json::array());
-    j["fn_function_keys"] = fn_function_keys_.to_json(make_default_fn_function_keys_json());
+    j["simple_modifications"] = simple_modifications_->to_json(nlohmann::json::array());
+    j["fn_function_keys"] = fn_function_keys_->to_json(make_default_fn_function_keys_json());
     j["complex_modifications"] = complex_modifications_.to_json();
     j["virtual_hid_keyboard"] = virtual_hid_keyboard_;
 
@@ -180,52 +182,14 @@ class profile final {
     return const_cast<details::parameters&>(static_cast<const profile&>(*this).get_parameters());
   }
 
-  const details::simple_modifications& get_simple_modifications(void) const {
+  gsl::not_null<std::shared_ptr<simple_modifications>> get_simple_modifications(void) const {
     return simple_modifications_;
   }
 
-  details::simple_modifications& get_simple_modifications(void) {
-    return const_cast<details::simple_modifications&>(static_cast<const profile&>(*this).get_simple_modifications());
-  }
-
-  const details::simple_modifications* find_simple_modifications(const device_identifiers& identifiers) const {
-    for (const auto& d : devices_) {
-      if (d->get_identifiers() == identifiers) {
-        return &(d->get_simple_modifications());
-      }
-    }
-    return nullptr;
-  }
-
-  details::simple_modifications* find_simple_modifications(const device_identifiers& identifiers) {
-    add_device(identifiers);
-
-    return const_cast<details::simple_modifications*>(static_cast<const profile&>(*this).find_simple_modifications(identifiers));
-  }
-
-  const details::simple_modifications& get_fn_function_keys(void) const {
+  gsl::not_null<std::shared_ptr<simple_modifications>> get_fn_function_keys(void) const {
     return fn_function_keys_;
   }
 
-  details::simple_modifications& get_fn_function_keys(void) {
-    return const_cast<details::simple_modifications&>(static_cast<const profile&>(*this).get_fn_function_keys());
-  }
-
-  const details::simple_modifications* find_fn_function_keys(const device_identifiers& identifiers) const {
-    for (const auto& d : devices_) {
-      if (d->get_identifiers() == identifiers) {
-        return &(d->get_fn_function_keys());
-      }
-    }
-    return nullptr;
-  }
-
-  details::simple_modifications* find_fn_function_keys(const device_identifiers& identifiers) {
-    add_device(identifiers);
-
-    return const_cast<details::simple_modifications*>(static_cast<const profile&>(*this).find_fn_function_keys(identifiers));
-  }
-
   const details::complex_modifications& get_complex_modifications(void) const {
     return complex_modifications_;
   }
@@ -288,37 +252,13 @@ class profile final {
   }
 
 private:
-  std::shared_ptr<details::device> find_device(const device_identifiers& identifiers) const {
-    auto it = std::find_if(std::begin(devices_),
-                           std::end(devices_),
-                           [&](auto&& d) {
-                             return d->get_identifiers() == identifiers;
-                           });
-    if (it != std::end(devices_)) {
-      return *it;
-    }
-    return nullptr;
-  }
-
-  gsl::not_null<std::shared_ptr<details::device>> add_device(const device_identifiers& identifiers) const {
-    if (auto d = find_device(identifiers)) {
-      return d;
-    }
-
-    devices_.push_back(std::make_shared<details::device>(nlohmann::json({
-                                                             {"identifiers", identifiers},
-                                                         }),
-                                                         error_handling_));
-    return devices_.back();
-  }
-
   nlohmann::json json_;
   error_handling error_handling_;
   std::string name_;
   bool selected_;
   details::parameters parameters_;
-  details::simple_modifications simple_modifications_;
-  details::simple_modifications fn_function_keys_;
+  gsl::not_null<std::shared_ptr<simple_modifications>> simple_modifications_;
+  gsl::not_null<std::shared_ptr<simple_modifications>> fn_function_keys_;
   details::complex_modifications complex_modifications_;
   details::virtual_hid_keyboard virtual_hid_keyboard_;
   mutable std::vector<gsl::not_null<std::shared_ptr<details::device>>> devices_;
diff --git a/src/share/core_configuration/details/profile/device.hpp b/src/share/core_configuration/details/profile/device.hpp
index 286598de1..2347de533 100644
--- a/src/share/core_configuration/details/profile/device.hpp
+++ b/src/share/core_configuration/details/profile/device.hpp
@@ -21,7 +21,9 @@ class device final {
 
   device(const nlohmann::json& json,
          error_handling error_handling)
-      : json_(json) {
+      : json_(json),
+        simple_modifications_(std::make_shared<simple_modifications>()),
+        fn_function_keys_(std::make_shared<simple_modifications>()) {
     helper_values_.push_back_value<bool>("ignore",
                                          ignore_,
                                          false);
@@ -162,15 +164,15 @@ if (abs(cos(radian)) <= abs(sin(radian))) {
 
 )");
 
-    // ----------------------------------------
+    //
     // Set default value
+    //
 
-    // fn_function_keys_
-
-    fn_function_keys_.update(make_default_fn_function_keys_json());
+    fn_function_keys_->update(make_default_fn_function_keys_json());
 
-    // ----------------------------------------
+    //
     // Load from json
+    //
 
     pqrs::json::requires_object(json, "json");
 
@@ -185,14 +187,14 @@ if (abs(cos(radian)) <= abs(sin(radian))) {
         }
       } else if (key == "simple_modifications") {
         try {
-          simple_modifications_.update(value);
+          simple_modifications_->update(value);
         } catch (const pqrs::json::unmarshal_error& e) {
           throw pqrs::json::unmarshal_error(fmt::format("`{0}` error: {1}", key, e.what()));
         }
 
       } else if (key == "fn_function_keys") {
         try {
-          fn_function_keys_.update(value);
+          fn_function_keys_->update(value);
         } catch (const pqrs::json::unmarshal_error& e) {
           throw pqrs::json::unmarshal_error(fmt::format("`{0}` error: {1}", key, e.what()));
         }
@@ -248,7 +250,7 @@ if (abs(cos(radian)) <= abs(sin(radian))) {
     j["identifiers"] = identifiers_;
 
     {
-      auto jj = simple_modifications_.to_json(nlohmann::json::array());
+      auto jj = simple_modifications_->to_json(nlohmann::json::array());
       if (!jj.empty()) {
         j["simple_modifications"] = jj;
       } else {
@@ -257,7 +259,7 @@ if (abs(cos(radian)) <= abs(sin(radian))) {
     }
 
     {
-      auto jj = fn_function_keys_.to_json(make_default_fn_function_keys_json());
+      auto jj = fn_function_keys_->to_json(make_default_fn_function_keys_json());
       if (!jj.empty()) {
         j["fn_function_keys"] = jj;
       } else {
@@ -505,17 +507,11 @@ if (abs(cos(radian)) <= abs(sin(radian))) {
     coordinate_between_properties();
   }
 
-  const simple_modifications& get_simple_modifications(void) const {
-    return simple_modifications_;
-  }
-  simple_modifications& get_simple_modifications(void) {
+  gsl::not_null<std::shared_ptr<simple_modifications>> get_simple_modifications(void) const {
     return simple_modifications_;
   }
 
-  const simple_modifications& get_fn_function_keys(void) const {
-    return fn_function_keys_;
-  }
-  simple_modifications& get_fn_function_keys(void) {
+  gsl::not_null<std::shared_ptr<simple_modifications>> get_fn_function_keys(void) const {
     return fn_function_keys_;
   }
 
@@ -571,8 +567,8 @@ if (abs(cos(radian)) <= abs(sin(radian))) {
   std::string game_pad_stick_y_formula_;
   std::string game_pad_stick_vertical_wheel_formula_;
   std::string game_pad_stick_horizontal_wheel_formula_;
-  simple_modifications simple_modifications_;
-  simple_modifications fn_function_keys_;
+  gsl::not_null<std::shared_ptr<simple_modifications>> simple_modifications_;
+  gsl::not_null<std::shared_ptr<simple_modifications>> fn_function_keys_;
   configuration_json_helper::helper_values helper_values_;
 };
 
diff --git a/tests/src/core_configuration/src/core_configuration_test.hpp b/tests/src/core_configuration/src/core_configuration_test.hpp
index ebc70be7b..69808f331 100644
--- a/tests/src/core_configuration/src/core_configuration_test.hpp
+++ b/tests/src/core_configuration/src/core_configuration_test.hpp
@@ -35,7 +35,7 @@ void run_core_configuration_test(void) {
       expected.emplace_back(nlohmann::json::object({{"key_code", "escape"}}).dump(),
                             nlohmann::json::array({nlohmann::json::object({{"key_code", "spacebar"}})}).dump());
 
-      expect(expected == configuration.get_selected_profile().get_simple_modifications().get_pairs()) << UT_SHOW_LINE;
+      expect(expected == configuration.get_selected_profile().get_simple_modifications()->get_pairs()) << UT_SHOW_LINE;
     }
     {
       auto manipulator = configuration.get_selected_profile().get_complex_modifications().get_rules()[0].get_manipulators()[0].get_json();
@@ -81,7 +81,7 @@ void run_core_configuration_test(void) {
       expected.emplace_back(nlohmann::json::object({{"key_code", "f12"}}).dump(),
                             nlohmann::json::array({nlohmann::json::object({{"consumer_key_code", "volume_increment"}})}).dump());
 
-      expect(expected == configuration.get_selected_profile().get_fn_function_keys().get_pairs()) << UT_SHOW_LINE;
+      expect(expected == configuration.get_selected_profile().get_fn_function_keys()->get_pairs()) << UT_SHOW_LINE;
     }
     {
       auto& complex_modifications = configuration.get_selected_profile().get_complex_modifications();
@@ -149,7 +149,7 @@ void run_core_configuration_test(void) {
                                                                  geteuid(),
                                                                  krbn::core_configuration::error_handling::strict);
 
-      expect(configuration.get_selected_profile().get_simple_modifications().get_pairs().empty());
+      expect(configuration.get_selected_profile().get_simple_modifications()->get_pairs().empty());
       expect(configuration.is_loaded() == false);
 
       expect(configuration.get_global_configuration().get_check_for_updates_on_startup() == true);
@@ -160,7 +160,7 @@ void run_core_configuration_test(void) {
       expect(configuration.get_profiles().size() == 1);
       expect((configuration.get_profiles())[0]->get_name() == "Default profile");
       expect((configuration.get_profiles())[0]->get_selected() == true);
-      expect((configuration.get_profiles())[0]->get_fn_function_keys().get_pairs().size() == 12);
+      expect((configuration.get_profiles())[0]->get_fn_function_keys()->get_pairs().size() == 12);
 
       {
         // to_json result is default json if is_loaded == false
@@ -174,7 +174,7 @@ void run_core_configuration_test(void) {
                                                                  geteuid(),
                                                                  krbn::core_configuration::error_handling::strict);
 
-      expect(configuration.get_selected_profile().get_simple_modifications().get_pairs().empty());
+      expect(configuration.get_selected_profile().get_simple_modifications()->get_pairs().empty());
       expect(configuration.is_loaded() == false);
     }
   };
@@ -192,7 +192,7 @@ void run_core_configuration_test(void) {
     expected.emplace_back(nlohmann::json::object({{"key_code", "escape"}}).dump(),
                           nlohmann::json::array({nlohmann::json::object({{"key_code", "spacebar"}})}).dump());
 
-    expect(configuration.get_selected_profile().get_simple_modifications().get_pairs() == expected);
+    expect(configuration.get_selected_profile().get_simple_modifications()->get_pairs() == expected);
     expect(configuration.is_loaded() == true);
   };
 
@@ -289,8 +289,8 @@ void run_core_configuration_test(void) {
                                                          krbn::core_configuration::error_handling::strict);
       expect(profile.get_name() == std::string(""));
       expect(profile.get_selected() == false);
-      expect(profile.get_simple_modifications().get_pairs().empty());
-      expect(profile.get_fn_function_keys().get_pairs().size() == 12);
+      expect(profile.get_simple_modifications()->get_pairs().empty());
+      expect(profile.get_fn_function_keys()->get_pairs().size() == 12);
       expect(profile.get_devices().size() == 0);
 
       expect(profile.get_device(krbn::device_identifiers(pqrs::hid::vendor_id::value_t(4176),
@@ -443,7 +443,7 @@ void run_core_configuration_test(void) {
         expected.emplace_back(nlohmann::json::object({{"key_code", "from 10"}}).dump(),
                               nlohmann::json::array({nlohmann::json::object({{"key_code", "to 10"}})}).dump());
 
-        expect(profile.get_simple_modifications().get_pairs() == expected) << UT_SHOW_LINE;
+        expect(profile.get_simple_modifications()->get_pairs() == expected) << UT_SHOW_LINE;
       }
       {
         std::vector<std::pair<std::string, std::string>> expected;
@@ -486,7 +486,7 @@ void run_core_configuration_test(void) {
         expected.emplace_back(nlohmann::json::object({{"key_code", "f13"}}).dump(),
                               nlohmann::json::array({nlohmann::json::object({{"key_code", "to f13"}})}).dump());
 
-        expect(expected == profile.get_fn_function_keys().get_pairs()) << UT_SHOW_LINE;
+        expect(expected == profile.get_fn_function_keys()->get_pairs()) << UT_SHOW_LINE;
       }
       {
         expect(profile.get_devices().size() == 3);
@@ -662,7 +662,7 @@ void run_core_configuration_test(void) {
         expected.emplace_back(nlohmann::json::object({{"key_code", "key"}}).dump(),
                               nlohmann::json::array({nlohmann::json::object({{"key_code", "value"}})}).dump());
 
-        expect(expected == profile.get_simple_modifications().get_pairs()) << UT_SHOW_LINE;
+        expect(expected == profile.get_simple_modifications()->get_pairs()) << UT_SHOW_LINE;
       }
     }
   };
@@ -732,34 +732,34 @@ void run_core_configuration_test(void) {
 
       profile.get_parameters().set_delay_milliseconds_before_open_device(std::chrono::milliseconds(500));
 
-      profile.get_simple_modifications().push_back_pair();
+      profile.get_simple_modifications()->push_back_pair();
       // {
       //   "": ""
       // }
 
-      profile.get_simple_modifications().push_back_pair();
-      profile.get_simple_modifications().replace_pair(1,
-                                                      nlohmann::json{{"key_code", "from 1"}}.dump(),
-                                                      nlohmann::json{{"key_code", "to 1"}}.dump());
+      profile.get_simple_modifications()->push_back_pair();
+      profile.get_simple_modifications()->replace_pair(1,
+                                                       nlohmann::json{{"key_code", "from 1"}}.dump(),
+                                                       nlohmann::json{{"key_code", "to 1"}}.dump());
       // {
       //   "": "",
       //   "from 1": "to 1"
       // }
 
-      profile.get_simple_modifications().push_back_pair();
-      profile.get_simple_modifications().replace_pair(2,
-                                                      nlohmann::json{{"key_code", "from 3"}}.dump(),
-                                                      nlohmann::json{{"key_code", "to 3"}}.dump());
+      profile.get_simple_modifications()->push_back_pair();
+      profile.get_simple_modifications()->replace_pair(2,
+                                                       nlohmann::json{{"key_code", "from 3"}}.dump(),
+                                                       nlohmann::json{{"key_code", "to 3"}}.dump());
       // {
       //   "": "",
       //   "from 1": "to 1",
       //   "from 3": "to 3"
       // }
 
-      profile.get_simple_modifications().push_back_pair();
-      profile.get_simple_modifications().replace_pair(3,
-                                                      nlohmann::json{{"key_code", "from 4"}}.dump(),
-                                                      nlohmann::json{{"key_code", "to 4"}}.dump());
+      profile.get_simple_modifications()->push_back_pair();
+      profile.get_simple_modifications()->replace_pair(3,
+                                                       nlohmann::json{{"key_code", "from 4"}}.dump(),
+                                                       nlohmann::json{{"key_code", "to 4"}}.dump());
       // {
       //   "": "",
       //   "from 1": "to 1",
@@ -767,10 +767,10 @@ void run_core_configuration_test(void) {
       //   "from 4": "to 4"
       // }
 
-      profile.get_simple_modifications().push_back_pair();
-      profile.get_simple_modifications().replace_pair(4,
-                                                      nlohmann::json{{"key_code", "from 2"}}.dump(),
-                                                      nlohmann::json{{"key_code", "to 2"}}.dump());
+      profile.get_simple_modifications()->push_back_pair();
+      profile.get_simple_modifications()->replace_pair(4,
+                                                       nlohmann::json{{"key_code", "from 2"}}.dump(),
+                                                       nlohmann::json{{"key_code", "to 2"}}.dump());
       // {
       //   "": "",
       //   "from 1": "to 1",
@@ -779,10 +779,10 @@ void run_core_configuration_test(void) {
       //   "from 2": "to 2"
       // }
 
-      profile.get_simple_modifications().push_back_pair();
-      profile.get_simple_modifications().replace_pair(5,
-                                                      nlohmann::json{{"key_code", "from 2"}}.dump(),
-                                                      nlohmann::json{{"key_code", "to 2.0"}}.dump());
+      profile.get_simple_modifications()->push_back_pair();
+      profile.get_simple_modifications()->replace_pair(5,
+                                                       nlohmann::json{{"key_code", "from 2"}}.dump(),
+                                                       nlohmann::json{{"key_code", "to 2.0"}}.dump());
       // {
       //   "": "",
       //   "from 1": "to 1",
@@ -792,7 +792,7 @@ void run_core_configuration_test(void) {
       //   "from 2": "to 2.0"
       // }
 
-      profile.get_simple_modifications().erase_pair(2);
+      profile.get_simple_modifications()->erase_pair(2);
       // {
       //   "": "",
       //   "from 1": "to 1",
@@ -801,10 +801,10 @@ void run_core_configuration_test(void) {
       //   "from 2": "to 2.0"
       // }
 
-      profile.get_simple_modifications().push_back_pair();
-      profile.get_simple_modifications().replace_pair(5,
-                                                      nlohmann::json::object().dump(),
-                                                      nlohmann::json{{"key_code", "to 0"}}.dump());
+      profile.get_simple_modifications()->push_back_pair();
+      profile.get_simple_modifications()->replace_pair(5,
+                                                       nlohmann::json::object().dump(),
+                                                       nlohmann::json{{"key_code", "to 0"}}.dump());
       // {
       //   "": "",
       //   "from 1": "to 1",
@@ -814,10 +814,10 @@ void run_core_configuration_test(void) {
       //   "": "to 0"
       // }
 
-      profile.get_simple_modifications().push_back_pair();
-      profile.get_simple_modifications().replace_pair(6,
-                                                      nlohmann::json{{"key_code", "from 0"}}.dump(),
-                                                      nlohmann::json::object().dump());
+      profile.get_simple_modifications()->push_back_pair();
+      profile.get_simple_modifications()->replace_pair(6,
+                                                       nlohmann::json{{"key_code", "from 0"}}.dump(),
+                                                       nlohmann::json::object().dump());
       // {
       //   "": "",
       //   "from 1": "to 1",
@@ -828,10 +828,10 @@ void run_core_configuration_test(void) {
       //   "from 0": ""
       // }
 
-      profile.get_simple_modifications().push_back_pair();
-      profile.get_simple_modifications().replace_pair(7,
-                                                      nlohmann::json{{"key_code", "from 5"}}.dump(),
-                                                      nlohmann::json{{"key_code", "to 5"}}.dump());
+      profile.get_simple_modifications()->push_back_pair();
+      profile.get_simple_modifications()->replace_pair(7,
+                                                       nlohmann::json{{"key_code", "from 5"}}.dump(),
+                                                       nlohmann::json{{"key_code", "to 5"}}.dump());
       // {
       //   "": "",
       //   "from 1": "to 1",
@@ -843,10 +843,10 @@ void run_core_configuration_test(void) {
       //   "from 5": "to 5"
       // }
 
-      profile.get_fn_function_keys().replace_second(nlohmann::json{{"key_code", "f3"}}.dump(),
-                                                    nlohmann::json{{"key_code", "to f3"}}.dump());
-      profile.get_fn_function_keys().replace_second(nlohmann::json{{"key_code", "not found"}}.dump(),
-                                                    nlohmann::json{{"key_code", "do nothing"}}.dump());
+      profile.get_fn_function_keys()->replace_second(nlohmann::json{{"key_code", "f3"}}.dump(),
+                                                     nlohmann::json{{"key_code", "to f3"}}.dump());
+      profile.get_fn_function_keys()->replace_second(nlohmann::json{{"key_code", "not found"}}.dump(),
+                                                     nlohmann::json{{"key_code", "do nothing"}}.dump());
 
       profile.get_virtual_hid_keyboard().set_country_code(pqrs::hid::country_code::value_t(20));
       profile.get_virtual_hid_keyboard().set_mouse_key_xy_scale(250);