diff --git a/code/espurna/relay.cpp b/code/espurna/relay.cpp
index f0fe7d48..c3a8d46f 100644
--- a/code/espurna/relay.cpp
+++ b/code/espurna/relay.cpp
@@ -1096,7 +1096,7 @@ PayloadStatus relayParsePayload(const char * payload) {
 void _relayBackwards() {
 
     for (unsigned char id = 0; id < _relays.size(); ++id) {
-        const settings_key_t key {"mqttGroupInv", id};
+        SettingsKey key {"mqttGroupInv", id};
         if (!hasSetting(key)) continue;
         setSetting({"mqttGroupSync", id}, getSetting(key));
         delSetting(key);
diff --git a/code/espurna/rfbridge.cpp b/code/espurna/rfbridge.cpp
index a24abc07..52c23f84 100644
--- a/code/espurna/rfbridge.cpp
+++ b/code/espurna/rfbridge.cpp
@@ -1131,7 +1131,7 @@ void _rfbInitCommands() {
 // -----------------------------------------------------------------------------
 
 void rfbStore(unsigned char id, bool status, const char * code) {
-    settings_key_t key { status ? F("rfbON") : F("rfbOFF"), id };
+    SettingsKey key { status ? F("rfbON") : F("rfbOFF"), id };
     setSetting(key, code);
     DEBUG_MSG_P(PSTR("[RF] Saved %s => \"%s\"\n"), key.toString().c_str(), code);
 }
@@ -1214,12 +1214,12 @@ void _rfbSettingsMigrate(int version) {
     String buffer;
 
     for (unsigned char index = 0; index < relayCount(); ++index) {
-        const settings_key_t on_key {F("rfbON"), index};
+        SettingsKey on_key {F("rfbON"), index};
         if (migrate_code(buffer, getSetting(on_key))) {
             setSetting(on_key, buffer);
         }
 
-        const settings_key_t off_key {F("rfbOFF"), index};
+        SettingsKey off_key {F("rfbOFF"), index};
         if (migrate_code(buffer, getSetting(off_key))) {
             setSetting(off_key, buffer);
         }
diff --git a/code/espurna/sensor.cpp b/code/espurna/sensor.cpp
index 7814c05c..936b3f2e 100644
--- a/code/espurna/sensor.cpp
+++ b/code/espurna/sensor.cpp
@@ -1051,7 +1051,7 @@ const String _sensorQueryDefault(const String& key) {
         }
     };
 
-    auto magnitude_key = [](const sensor_magnitude_t& magnitude) -> settings_key_t {
+    auto magnitude_key = [](const sensor_magnitude_t& magnitude) -> SettingsKey {
         switch (magnitude.type) {
         case MAGNITUDE_CURRENT:
             return {"pwrRatioC", magnitude.index_global};
@@ -1076,7 +1076,7 @@ const String _sensorQueryDefault(const String& key) {
             case MAGNITUDE_POWER_ACTIVE:
             case MAGNITUDE_ENERGY: {
                 auto ratioKey(magnitude_key(magnitude));
-                if (ratioKey.match(key)) {
+                if (ratioKey == key) {
                     target = magnitude.sensor;
                     type = magnitude.type;
                     goto return_defaults;
diff --git a/code/espurna/settings.cpp b/code/espurna/settings.cpp
index e56fd7d2..f75b68cb 100644
--- a/code/espurna/settings.cpp
+++ b/code/espurna/settings.cpp
@@ -235,14 +235,6 @@ String settingsQueryDefaults(const String& key) {
 // Key-value API
 // -----------------------------------------------------------------------------
 
-String settings_key_t::toString() const {
-    if (_index < 0) {
-        return _value;
-    } else {
-        return _value + _index;
-    }
-}
-
 settings_move_key_t _moveKeys(const String& from, const String& to, unsigned char index) {
     return settings_move_key_t {{from, index}, {to, index}};
 }
@@ -273,65 +265,81 @@ void moveSettings(const String& from, const String& to) {
     }
 }
 
-template<>
-String getSetting(const settings_key_t& key, String defaultValue) {
-    auto result = settings::kv_store.get(key.toString());
-    if (!result) {
-        return defaultValue;
-    }
-    return result.value;
-}
-
 template
-bool getSetting(const settings_key_t& key, bool defaultValue);
+bool getSetting(const SettingsKey& key, bool defaultValue);
 
 template
-int getSetting(const settings_key_t& key, int defaultValue);
+int getSetting(const SettingsKey& key, int defaultValue);
 
 template
-long getSetting(const settings_key_t& key, long defaultValue);
+long getSetting(const SettingsKey& key, long defaultValue);
 
 template
-unsigned char getSetting(const settings_key_t& key, unsigned char defaultValue);
+unsigned char getSetting(const SettingsKey& key, unsigned char defaultValue);
 
 template
-unsigned short getSetting(const settings_key_t& key, unsigned short defaultValue);
+unsigned short getSetting(const SettingsKey& key, unsigned short defaultValue);
 
 template
-unsigned int getSetting(const settings_key_t& key, unsigned int defaultValue);
+unsigned int getSetting(const SettingsKey& key, unsigned int defaultValue);
 
 template
-unsigned long getSetting(const settings_key_t& key, unsigned long defaultValue);
+unsigned long getSetting(const SettingsKey& key, unsigned long defaultValue);
 
 template
-float getSetting(const settings_key_t& key, float defaultValue);
+float getSetting(const SettingsKey& key, float defaultValue);
 
 template
-double getSetting(const settings_key_t& key, double defaultValue);
+double getSetting(const SettingsKey& key, double defaultValue);
+
+String getSetting(const String& key) {
+    return settings::kv_store.get(key).value;
+}
 
-String getSetting(const settings_key_t& key) {
+String getSetting(const __FlashStringHelper* key) {
+    return getSetting(String(key));
+}
+
+String getSetting(const char* key) {
+    return getSetting(String(key));
+}
+
+String getSetting(const SettingsKey& key) {
     static const String defaultValue("");
     return getSetting(key, defaultValue);
 }
 
-String getSetting(const settings_key_t& key, const char* defaultValue) {
-    return getSetting(key, String(defaultValue));
+String getSetting(const SettingsKey& key, const char* defaultValue) {
+    return getSetting(key, std::move(String(defaultValue)));
 }
 
-String getSetting(const settings_key_t& key, const __FlashStringHelper* defaultValue) {
-    return getSetting(key, String(defaultValue));
+String getSetting(const SettingsKey& key, const __FlashStringHelper* defaultValue) {
+    return getSetting(key, std::move(String(defaultValue)));
 }
 
-template<>
-bool setSetting(const settings_key_t& key, const String& value) {
-    return settings::kv_store.set(key.toString(), value);
+String getSetting(const SettingsKey& key, const String& defaultValue) {
+    auto result = settings::kv_store.get(key.toString());
+    if (!result) {
+        result.value = defaultValue;
+    }
+
+    return result.value;
+}
+
+String getSetting(const SettingsKey& key, String&& defaultValue) {
+    auto result = settings::kv_store.get(key.toString());
+    if (!result) {
+        result.value = std::move(defaultValue);
+    }
+
+    return result.value;
 }
 
-bool delSetting(const settings_key_t& key) {
+bool delSetting(const SettingsKey& key) {
     return settings::kv_store.del(key.toString());
 }
 
-bool hasSetting(const settings_key_t& key) {
+bool hasSetting(const SettingsKey& key) {
     return settings::kv_store.has(key.toString());
 }
 
diff --git a/code/espurna/settings.h b/code/espurna/settings.h
index 4fe78d3e..51a6d961 100644
--- a/code/espurna/settings.h
+++ b/code/espurna/settings.h
@@ -53,51 +53,63 @@ extern kvs_type kv_store;
 
 // --------------------------------------------------------------------------
 
-class settings_key_t {
-
-    public:
-        settings_key_t(const char* value, unsigned char index) :
-            _value(value), _index(index)
-        {}
-        settings_key_t(const String& value, unsigned char index) :
-            _value(value), _index(index)
-        {}
-        settings_key_t(String&& value, unsigned char index) :
-            _value(std::move(value)), _index(index)
-        {}
-        settings_key_t(const char* value) :
-            _value(value), _index(-1)
-        {}
-        settings_key_t(const String& value) :
-            _value(value), _index(-1)
-        {}
-        settings_key_t(const __FlashStringHelper* value) :
-            _value(value), _index(-1)
-        {}
-        settings_key_t() :
-            _value(), _index(-1)
-        {}
-
-        bool match(const char* value) const {
-            return (_value == value) || (toString() == value);
-        }
-
-        bool match(const String& value) const {
-            return (_value == value) || (toString() == value);
-        }
-
-        String toString() const;
-
-        explicit operator String () const {
-            return toString();
-        }
-
-    private:
-        const String _value;
-        int _index;
+class SettingsKey {
+public:
+    SettingsKey(const char* key) :
+        _key(key)
+    {}
+
+    SettingsKey(const String& key) :
+        _key(key)
+    {}
+
+    SettingsKey(String&& key) :
+        _key(std::move(key))
+    {}
+
+    SettingsKey(const String& prefix, unsigned char index) {
+        _key.reserve(prefix.length());
+        _key += prefix;
+        _key += index;
+    }
+
+    SettingsKey(String&& prefix, unsigned char index) :
+        _key(std::move(prefix))
+    {
+        _key += index;
+    }
+
+    SettingsKey(const char* prefix, unsigned char index) :
+        _key(prefix)
+    {
+        _key += index;
+    }
+
+    bool operator==(const char* other) const {
+        return _key == other;
+    }
+
+    bool operator==(const String& other) const {
+        return _key == other;
+    }
+
+    const String& toString() const {
+        return _key;
+    }
+
+    explicit operator String() const & {
+        return _key;
+    }
+
+    explicit operator String() && {
+        return std::move(_key);
+    }
+
+private:
+    String _key;
 };
 
-using settings_move_key_t = std::pair<settings_key_t, settings_key_t>;
+using settings_move_key_t = std::pair<SettingsKey, SettingsKey>;
 using settings_filter_t = std::function<String(String& value)>;
 
 // --------------------------------------------------------------------------
@@ -121,13 +133,13 @@ using is_arduino_string = std::is_same<String, typename std::decay<T>::type>;
 template <typename T>
 using enable_if_arduino_string = std::enable_if<is_arduino_string<T>::value>;
 
+template <typename T>
+using enable_if_not_arduino_string = std::enable_if<!is_arduino_string<T>::value>;
+
 // --------------------------------------------------------------------------
 
 uint32_t u32fromString(const String& string, int base);
 
-template <typename T>
-using convert_t = T(*)(const String& value);
-
 template <typename T>
 T convert(const String& value);
 
@@ -188,35 +200,41 @@ void moveSetting(const String& from, const String& to);
 void moveSetting(const String& from, const String& to, unsigned int index);
 void moveSettings(const String& from, const String& to);
 
-template<typename R, settings::internal::convert_t<R> Rfunc = settings::internal::convert>
-R getSetting(const settings_key_t& key, R defaultValue) __attribute__((noinline));
+template <typename T, typename = typename settings::internal::enable_if_not_arduino_string<T>::type>
+T getSetting(const SettingsKey& key, T defaultValue) __attribute__((noinline));
 
-template<typename R, settings::internal::convert_t<R> Rfunc = settings::internal::convert>
-R getSetting(const settings_key_t& key, R defaultValue) {
+template <typename T, typename = typename settings::internal::enable_if_not_arduino_string<T>::type>
+T getSetting(const SettingsKey& key, T defaultValue) {
     auto result = settings::kv_store.get(key.toString());
     if (!result) {
         return defaultValue;
     }
-    return Rfunc(result.value);
+    return settings::internal::convert<T>(result.value);
 }
 
-template<>
-String getSetting(const settings_key_t& key, String defaultValue);
+String getSetting(const char* key);
+String getSetting(const String& key);
+String getSetting(const __FlashStringHelper* key);
 
-String getSetting(const settings_key_t& key);
-String getSetting(const settings_key_t& key, const char* defaultValue);
-String getSetting(const settings_key_t& key, const __FlashStringHelper* defaultValue);
+String getSetting(const SettingsKey& key);
+String getSetting(const SettingsKey& key, const char* defaultValue);
+String getSetting(const SettingsKey& key, const __FlashStringHelper* defaultValue);
+String getSetting(const SettingsKey& key, const String& defaultValue);
+String getSetting(const SettingsKey& key, const String& defaultValue);
+String getSetting(const SettingsKey& key, String&& defaultValue);
 
-template<typename T>
-bool setSetting(const settings_key_t& key, const T& value) {
-    return settings::kv_store.set(key.toString(), String(value));
+template<typename T, typename = typename settings::internal::enable_if_arduino_string<T>::type>
+bool setSetting(const SettingsKey& key, T&& value) {
+    return settings::kv_store.set(key.toString(), value);
 }
 
-template<>
-bool setSetting(const settings_key_t& key, const String& value);
+template<typename T, typename = typename settings::internal::enable_if_not_arduino_string<T>::type>
+bool setSetting(const SettingsKey& key, T value) {
+    return setSetting(key, std::move(String(value)));
+}
 
-bool delSetting(const settings_key_t& key);
-bool hasSetting(const settings_key_t& key);
+bool delSetting(const SettingsKey& key);
+bool hasSetting(const SettingsKey& key);
 
 void saveSettings();
 void resetSettings();
diff --git a/code/espurna/ws.cpp b/code/espurna/ws.cpp
index ac4fc6f4..b1855171 100644
--- a/code/espurna/ws.cpp
+++ b/code/espurna/ws.cpp
@@ -271,9 +271,9 @@ bool _wsStore(const String& key, JsonArray& values) {
     unsigned char index = 0;
     for (auto& element : values) {
         const auto value = element.as<String>();
-        const auto keyobj = settings_key_t {key, index};
-        if (!hasSetting(keyobj) || value != getSetting(keyobj)) {
-            setSetting(keyobj, value);
+        auto setting = SettingsKey {key, index};
+        if (!hasSetting(setting) || value != getSetting(setting)) {
+            setSetting(setting, value);
             changed = true;
         }
         ++index;