diff --git a/include/WebApi_mqtt.h b/include/WebApi_mqtt.h
index 56e26541..99a494f7 100644
--- a/include/WebApi_mqtt.h
+++ b/include/WebApi_mqtt.h
@@ -14,7 +14,7 @@ private:
     void onMqttStatus(AsyncWebServerRequest* request);
     void onMqttAdminGet(AsyncWebServerRequest* request);
     void onMqttAdminPost(AsyncWebServerRequest* request);
-    String getRootCaCertInfo(char* cert);
+    String getRootCaCertInfo(const char* cert);
 
     AsyncWebServer* _server;
 };
\ No newline at end of file
diff --git a/lib/Hoymiles/src/crc.cpp b/lib/Hoymiles/src/crc.cpp
index 6f7a9913..ce3bbf90 100644
--- a/lib/Hoymiles/src/crc.cpp
+++ b/lib/Hoymiles/src/crc.cpp
@@ -1,6 +1,6 @@
 #include "crc.h"
 
-uint8_t crc8(uint8_t buf[], uint8_t len)
+uint8_t crc8(const uint8_t buf[], uint8_t len)
 {
     uint8_t crc = CRC8_INIT;
     for (uint8_t i = 0; i < len; i++) {
@@ -12,7 +12,7 @@ uint8_t crc8(uint8_t buf[], uint8_t len)
     return crc;
 }
 
-uint16_t crc16(uint8_t buf[], uint8_t len, uint16_t start)
+uint16_t crc16(const uint8_t buf[], uint8_t len, uint16_t start)
 {
     uint16_t crc = start;
     uint8_t shift = 0;
@@ -29,7 +29,7 @@ uint16_t crc16(uint8_t buf[], uint8_t len, uint16_t start)
     return crc;
 }
 
-uint16_t crc16nrf24(uint8_t buf[], uint16_t lenBits, uint16_t startBit, uint16_t crcIn)
+uint16_t crc16nrf24(const uint8_t buf[], uint16_t lenBits, uint16_t startBit, uint16_t crcIn)
 {
     uint16_t crc = crcIn;
     uint8_t idx, val = buf[(startBit >> 3)];
diff --git a/lib/Hoymiles/src/crc.h b/lib/Hoymiles/src/crc.h
index eaa7299f..dd640cc3 100644
--- a/lib/Hoymiles/src/crc.h
+++ b/lib/Hoymiles/src/crc.h
@@ -8,6 +8,6 @@
 #define CRC16_MODBUS_POLYNOM 0xA001
 #define CRC16_NRF24_POLYNOM 0x1021
 
-uint8_t crc8(uint8_t buf[], uint8_t len);
-uint16_t crc16(uint8_t buf[], uint8_t len, uint16_t start = 0xffff);
-uint16_t crc16nrf24(uint8_t buf[], uint16_t lenBits, uint16_t startBit = 0, uint16_t crcIn = 0xffff);
+uint8_t crc8(const uint8_t buf[], uint8_t len);
+uint16_t crc16(const uint8_t buf[], uint8_t len, uint16_t start = 0xffff);
+uint16_t crc16nrf24(const uint8_t buf[], uint16_t lenBits, uint16_t startBit = 0, uint16_t crcIn = 0xffff);
diff --git a/src/MqttHassPublishing.cpp b/src/MqttHassPublishing.cpp
index 99f46871..0ddebcef 100644
--- a/src/MqttHassPublishing.cpp
+++ b/src/MqttHassPublishing.cpp
@@ -46,7 +46,7 @@ void MqttHassPublishingClass::publishConfig()
         return;
     }
 
-    CONFIG_T& config = Configuration.get();
+    const CONFIG_T& config = Configuration.get();
 
     // Loop all inverters
     for (uint8_t i = 0; i < Hoymiles.getNumInverters(); i++) {
diff --git a/src/MqttPublishing.cpp b/src/MqttPublishing.cpp
index 9108689a..4b3477fd 100644
--- a/src/MqttPublishing.cpp
+++ b/src/MqttPublishing.cpp
@@ -19,7 +19,7 @@ void MqttPublishingClass::loop()
         return;
     }
 
-    CONFIG_T& config = Configuration.get();
+    const CONFIG_T& config = Configuration.get();
 
     if (millis() - _lastPublish > (config.Mqtt_PublishInterval * 1000)) {
         MqttSettings.publish("dtu/uptime", String(millis() / 1000));
diff --git a/src/MqttSettings.cpp b/src/MqttSettings.cpp
index 049a11f3..0c419524 100644
--- a/src/MqttSettings.cpp
+++ b/src/MqttSettings.cpp
@@ -30,7 +30,7 @@ void MqttSettingsClass::NetworkEvent(network_event event)
 void MqttSettingsClass::onMqttConnect(bool sessionPresent)
 {
     Serial.println(F("Connected to MQTT."));
-    CONFIG_T& config = Configuration.get();
+    const CONFIG_T& config = Configuration.get();
     publish(config.Mqtt_LwtTopic, config.Mqtt_LwtValue_Online);
 }
 
@@ -70,7 +70,7 @@ void MqttSettingsClass::performConnect()
     if (NetworkSettings.isConnected() && Configuration.get().Mqtt_Enabled) {
         using namespace std::placeholders;
         Serial.println(F("Connecting to MQTT..."));
-        CONFIG_T& config = Configuration.get();
+        const CONFIG_T& config = Configuration.get();
         willTopic = getPrefix() + config.Mqtt_LwtTopic;
         clientId = NetworkSettings.getApName();
         if (config.Mqtt_Tls) {
@@ -95,7 +95,7 @@ void MqttSettingsClass::performConnect()
 
 void MqttSettingsClass::performDisconnect()
 {
-    CONFIG_T& config = Configuration.get();
+    const CONFIG_T& config = Configuration.get();
     publish(config.Mqtt_LwtTopic, config.Mqtt_LwtValue_Offline);
     mqttClient->disconnect();
 }
@@ -146,7 +146,7 @@ void MqttSettingsClass::createMqttClientObject()
 {
     if (mqttClient != nullptr)
         delete mqttClient;
-    CONFIG_T& config = Configuration.get();
+    const CONFIG_T& config = Configuration.get();
     if (config.Mqtt_Tls) {
         mqttClient = static_cast<MqttClient*>(new espMqttClientSecure);
     } else {
diff --git a/src/WebApi_dtu.cpp b/src/WebApi_dtu.cpp
index 743bb92e..68f80154 100644
--- a/src/WebApi_dtu.cpp
+++ b/src/WebApi_dtu.cpp
@@ -26,7 +26,7 @@ void WebApiDtuClass::onDtuAdminGet(AsyncWebServerRequest* request)
 {
     AsyncJsonResponse* response = new AsyncJsonResponse();
     JsonObject root = response->getRoot();
-    CONFIG_T& config = Configuration.get();
+    const CONFIG_T& config = Configuration.get();
 
     // DTU Serial is read as HEX
     char buffer[sizeof(uint64_t) * 8 + 1];
diff --git a/src/WebApi_inverter.cpp b/src/WebApi_inverter.cpp
index db2d0344..2206afe7 100644
--- a/src/WebApi_inverter.cpp
+++ b/src/WebApi_inverter.cpp
@@ -32,7 +32,7 @@ void WebApiInverterClass::onInverterList(AsyncWebServerRequest* request)
     JsonObject root = response->getRoot();
     JsonArray data = root.createNestedArray(F("inverter"));
 
-    CONFIG_T& config = Configuration.get();
+    const CONFIG_T& config = Configuration.get();
 
     for (uint8_t i = 0; i < INV_MAX_COUNT; i++) {
         if (config.Inverter[i].Serial > 0) {
diff --git a/src/WebApi_mqtt.cpp b/src/WebApi_mqtt.cpp
index 8fa36d9f..840d778c 100644
--- a/src/WebApi_mqtt.cpp
+++ b/src/WebApi_mqtt.cpp
@@ -29,7 +29,7 @@ void WebApiMqttClass::onMqttStatus(AsyncWebServerRequest* request)
 {
     AsyncJsonResponse* response = new AsyncJsonResponse(false, MQTT_JSON_DOC_SIZE);
     JsonObject root = response->getRoot();
-    CONFIG_T& config = Configuration.get();
+    const CONFIG_T& config = Configuration.get();
 
     root[F("mqtt_enabled")] = config.Mqtt_Enabled;
     root[F("mqtt_hostname")] = config.Mqtt_Hostname;
@@ -56,7 +56,7 @@ void WebApiMqttClass::onMqttAdminGet(AsyncWebServerRequest* request)
 {
     AsyncJsonResponse* response = new AsyncJsonResponse(false, MQTT_JSON_DOC_SIZE);
     JsonObject root = response->getRoot();
-    CONFIG_T& config = Configuration.get();
+    const CONFIG_T& config = Configuration.get();
 
     root[F("mqtt_enabled")] = config.Mqtt_Enabled;
     root[F("mqtt_hostname")] = config.Mqtt_Hostname;
@@ -267,7 +267,7 @@ void WebApiMqttClass::onMqttAdminPost(AsyncWebServerRequest* request)
     MqttHassPublishing.forceUpdate();
 }
 
-String WebApiMqttClass::getRootCaCertInfo(char* cert)
+String WebApiMqttClass::getRootCaCertInfo(const char* cert)
 {
     char rootCaCertInfo[1024] = "";
 
diff --git a/src/WebApi_network.cpp b/src/WebApi_network.cpp
index 3254c4b4..839df473 100644
--- a/src/WebApi_network.cpp
+++ b/src/WebApi_network.cpp
@@ -53,7 +53,7 @@ void WebApiNetworkClass::onNetworkAdminGet(AsyncWebServerRequest* request)
 {
     AsyncJsonResponse* response = new AsyncJsonResponse();
     JsonObject root = response->getRoot();
-    CONFIG_T& config = Configuration.get();
+    const CONFIG_T& config = Configuration.get();
 
     root[F("hostname")] = config.WiFi_Hostname;
     root[F("dhcp")] = config.WiFi_Dhcp;
diff --git a/src/WebApi_ntp.cpp b/src/WebApi_ntp.cpp
index 0f230822..ba57cebc 100644
--- a/src/WebApi_ntp.cpp
+++ b/src/WebApi_ntp.cpp
@@ -28,7 +28,7 @@ void WebApiNtpClass::onNtpStatus(AsyncWebServerRequest* request)
 {
     AsyncJsonResponse* response = new AsyncJsonResponse();
     JsonObject root = response->getRoot();
-    CONFIG_T& config = Configuration.get();
+    const CONFIG_T& config = Configuration.get();
 
     root[F("ntp_server")] = config.Ntp_Server;
     root[F("ntp_timezone")] = config.Ntp_Timezone;
@@ -52,7 +52,7 @@ void WebApiNtpClass::onNtpAdminGet(AsyncWebServerRequest* request)
 {
     AsyncJsonResponse* response = new AsyncJsonResponse();
     JsonObject root = response->getRoot();
-    CONFIG_T& config = Configuration.get();
+    const CONFIG_T& config = Configuration.get();
 
     root[F("ntp_server")] = config.Ntp_Server;
     root[F("ntp_timezone")] = config.Ntp_Timezone;
diff --git a/src/main.cpp b/src/main.cpp
index eed7a9e2..0aa72ead 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -78,7 +78,7 @@ void setup()
 
     // Initialize inverter communication
     Serial.print(F("Initialize Hoymiles interface... "));
-    CONFIG_T& config = Configuration.get();
+    const CONFIG_T& config = Configuration.get();
     Hoymiles.init();
 
     Serial.println(F("  Setting radio PA level... "));