diff --git a/src/Sensors.h b/src/Sensors.h
index 7b0cc61..d481816 100644
--- a/src/Sensors.h
+++ b/src/Sensors.h
@@ -334,7 +334,7 @@ public:
 
     uint8_t valueId = (uint8_t) valueType;
     if (!isValidValueId(valueId)) {
-      return false;
+      return 0;
     }
     
     float value = 0.0f;
diff --git a/src/SensorsTask.h b/src/SensorsTask.h
index cba050e..135d20f 100644
--- a/src/SensorsTask.h
+++ b/src/SensorsTask.h
@@ -385,7 +385,7 @@ protected:
         continue;
       }
 
-      const float sensorResistance = value > 0.001f
+      const float sensorResistance = value > 1
         ? DEFAULT_NTC_REF_RESISTANCE / (DEFAULT_NTC_VREF / (float) value - 1.0f)
         : 0.0f;
       const float rawTemp = 1.0f / (
@@ -577,7 +577,7 @@ protected:
 
   bool subscribeToBleDevice(const uint8_t sensorId, NimBLEClient* pClient) {
     auto& sSensor = Sensors::settings[sensorId];
-    auto pAddress = pClient->getPeerAddress().toString().c_str();
+    auto pAddress = pClient->getPeerAddress().toString();
     
     NimBLERemoteService* pService = nullptr;
     NimBLERemoteCharacteristic* pChar = nullptr;
@@ -588,13 +588,13 @@ protected:
     if (!pService) {
       Log.straceln(
         FPSTR(L_SENSORS_BLE), F("Sensor #%hhu '%s': failed to find env service (%s) on device %s"),
-        sensorId, sSensor.name, serviceUuid.toString().c_str(), pAddress
+        sensorId, sSensor.name, serviceUuid.toString().c_str(), pAddress.c_str()
       );
 
     } else {
       Log.straceln(
         FPSTR(L_SENSORS_BLE), F("Sensor #%hhu '%s': found env service (%s) on device %s"),
-        sensorId, sSensor.name, serviceUuid.toString().c_str(), pAddress
+        sensorId, sSensor.name, serviceUuid.toString().c_str(), pAddress.c_str()
       );
 
       // 0x2A6E - Notify temperature x0.01C (pvvx)
@@ -606,7 +606,7 @@ protected:
         if (pChar && (pChar->canNotify() || pChar->canIndicate())) {
           Log.straceln(
             FPSTR(L_SENSORS_BLE), F("Sensor #%hhu '%s': found temp char (%s) in env service on device %s"),
-            sensorId, sSensor.name, charUuid.toString().c_str(), pAddress
+            sensorId, sSensor.name, charUuid.toString().c_str(), pAddress.c_str()
           );
 
           pChar->unsubscribe();
@@ -661,14 +661,14 @@ protected:
             Log.straceln(
               FPSTR(L_SENSORS_BLE), F("Sensor #%hhu '%s': subscribed to temp char (%s) in env service on device %s"),
               sensorId, sSensor.name,
-              charUuid.toString().c_str(), pAddress
+              charUuid.toString().c_str(), pAddress.c_str()
             );
 
           } else {
             Log.swarningln(
               FPSTR(L_SENSORS_BLE), F("Sensor #%hhu '%s': failed to subscribe to temp char (%s) in env service on device %s"),
               sensorId, sSensor.name,
-              charUuid.toString().c_str(), pAddress
+              charUuid.toString().c_str(), pAddress.c_str()
             );
           }
         }
@@ -683,7 +683,7 @@ protected:
         if (pChar && (pChar->canNotify() || pChar->canIndicate())) {
           Log.straceln(
             FPSTR(L_SENSORS_BLE), F("Sensor #%hhu '%s': found temp char (%s) in env service on device %s"),
-            sensorId, sSensor.name, charUuid.toString().c_str(), pAddress
+            sensorId, sSensor.name, charUuid.toString().c_str(), pAddress.c_str()
           );
 
           pChar->unsubscribe();
@@ -738,14 +738,14 @@ protected:
             Log.straceln(
               FPSTR(L_SENSORS_BLE), F("Sensor #%hhu '%s': subscribed to temp char (%s) in env service on device %s"),
               sensorId, sSensor.name,
-              charUuid.toString().c_str(), pAddress
+              charUuid.toString().c_str(), pAddress.c_str()
             );
 
           } else {
             Log.swarningln(
               FPSTR(L_SENSORS_BLE), F("Sensor #%hhu '%s': failed to subscribe to temp char (%s) in env service on device %s"),
               sensorId, sSensor.name,
-              charUuid.toString().c_str(), pAddress
+              charUuid.toString().c_str(), pAddress.c_str()
             );
           }
         }
@@ -754,7 +754,7 @@ protected:
       if (!tempNotifyCreated) {
         Log.swarningln(
           FPSTR(L_SENSORS_BLE), F("Sensor #%hhu '%s': not found supported temp chars in env service on device %s"),
-          sensorId, sSensor.name, pAddress
+          sensorId, sSensor.name, pAddress.c_str()
         );
 
         pClient->disconnect();
@@ -772,7 +772,7 @@ protected:
           if (pChar && (pChar->canNotify() || pChar->canIndicate())) {
             Log.straceln(
               FPSTR(L_SENSORS_BLE), F("Sensor #%hhu '%s': found humidity char (%s) in env service on device %s"),
-              sensorId, sSensor.name, charUuid.toString().c_str(), pAddress
+              sensorId, sSensor.name, charUuid.toString().c_str(), pAddress.c_str()
             );
 
             pChar->unsubscribe();
@@ -827,14 +827,14 @@ protected:
               Log.straceln(
                 FPSTR(L_SENSORS_BLE), F("Sensor #%hhu '%s': subscribed to humidity char (%s) in env service on device %s"),
                 sensorId, sSensor.name,
-                charUuid.toString().c_str(), pAddress
+                charUuid.toString().c_str(), pAddress.c_str()
               );
 
             } else {
               Log.swarningln(
                 FPSTR(L_SENSORS_BLE), F("Sensor #%hhu '%s': failed to subscribe to humidity char (%s) in env service on device %s"),
                 sensorId, sSensor.name,
-                charUuid.toString().c_str(), pAddress
+                charUuid.toString().c_str(), pAddress.c_str()
               );
             }
           }
@@ -843,7 +843,7 @@ protected:
         if (!humidityNotifyCreated) {
           Log.swarningln(
             FPSTR(L_SENSORS_BLE), F("Sensor #%hhu '%s': not found supported humidity chars in env service on device %s"),
-            sensorId, sSensor.name, pAddress
+            sensorId, sSensor.name, pAddress.c_str()
           );
         }
       }
@@ -857,13 +857,13 @@ protected:
       if (!pService) {
         Log.straceln(
           FPSTR(L_SENSORS_BLE), F("Sensor #%hhu '%s': failed to find battery service (%s) on device %s"),
-          sensorId, sSensor.name, serviceUuid.toString().c_str(), pAddress
+          sensorId, sSensor.name, serviceUuid.toString().c_str(), pAddress.c_str()
         );
 
       } else {
         Log.straceln(
           FPSTR(L_SENSORS_BLE), F("Sensor #%hhu '%s': found battery service (%s) on device %s"),
-          sensorId, sSensor.name, serviceUuid.toString().c_str(), pAddress
+          sensorId, sSensor.name, serviceUuid.toString().c_str(), pAddress.c_str()
         );
 
         // 0x2A19 - Notify the battery charge level 0..99% (pvvx)
@@ -875,7 +875,7 @@ protected:
           if (pChar && (pChar->canNotify() || pChar->canIndicate())) {
             Log.straceln(
               FPSTR(L_SENSORS_BLE), F("Sensor #%hhu '%s': found battery char (%s) in battery service on device %s"),
-              sensorId, sSensor.name, charUuid.toString().c_str(), pAddress
+              sensorId, sSensor.name, charUuid.toString().c_str(), pAddress.c_str()
             );
 
             pChar->unsubscribe();
@@ -930,14 +930,14 @@ protected:
               Log.straceln(
                 FPSTR(L_SENSORS_BLE), F("Sensor #%hhu '%s': subscribed to battery char (%s) in battery service on device %s"),
                 sensorId, sSensor.name,
-                charUuid.toString().c_str(), pAddress
+                charUuid.toString().c_str(), pAddress.c_str()
               );
 
             } else {
               Log.swarningln(
                 FPSTR(L_SENSORS_BLE), F("Sensor #%hhu '%s': failed to subscribe to battery char (%s) in battery service on device %s"),
                 sensorId, sSensor.name,
-                charUuid.toString().c_str(), pAddress
+                charUuid.toString().c_str(), pAddress.c_str()
               );
             }
           }
@@ -946,7 +946,7 @@ protected:
         if (!batteryNotifyCreated) {
           Log.swarningln(
             FPSTR(L_SENSORS_BLE), F("Sensor #%hhu '%s': not found supported battery chars in battery service on device %s"),
-            sensorId, sSensor.name, pAddress
+            sensorId, sSensor.name, pAddress.c_str()
           );
         }
       }
diff --git a/src/Settings.h b/src/Settings.h
index af71a46..17cdad1 100644
--- a/src/Settings.h
+++ b/src/Settings.h
@@ -170,15 +170,15 @@ struct Settings {
   struct {
     struct {
       bool enabled = false;
-      byte gpio = GPIO_IS_NOT_CONFIGURED;
-      byte invertState = false;
+      uint8_t gpio = GPIO_IS_NOT_CONFIGURED;
+      bool invertState = false;
       unsigned short thresholdTime = 60;
     } input;
 
     struct {
       bool enabled = false;
-      byte gpio = GPIO_IS_NOT_CONFIGURED;
-      byte invertState = false;
+      uint8_t gpio = GPIO_IS_NOT_CONFIGURED;
+      bool invertState = false;
       unsigned short thresholdTime = 60;
       bool onFault = true;
       bool onLossConnection = true;
diff --git a/src/utils.h b/src/utils.h
index 4913357..ac4ffa2 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -72,7 +72,7 @@ time_t mkgmtime(const struct tm *ptm) {
 
 inline bool isDigit(const char* ptr) {
   char* endPtr;
-  strtol(ptr, &endPtr, 10);
+  auto tmp = strtol(ptr, &endPtr, 10);
   return *endPtr == 0;
 }
 
@@ -1324,7 +1324,7 @@ bool jsonToSettings(const JsonVariantConst src, Settings& dst, bool safe = false
   if (!src[FPSTR(S_HEATING)][FPSTR(S_MIN_TEMP)].isNull()) {
     unsigned char value = src[FPSTR(S_HEATING)][FPSTR(S_MIN_TEMP)].as<unsigned char>();
 
-    if (value != dst.heating.minTemp && value >= vars.slave.heating.minTemp && value < vars.slave.heating.maxTemp && value != dst.heating.minTemp) {
+    if (value != dst.heating.minTemp && value >= vars.slave.heating.minTemp && value < vars.slave.heating.maxTemp && value != dst.heating.maxTemp) {
       dst.heating.minTemp = value;
       changed = true;
     }
@@ -1333,7 +1333,7 @@ bool jsonToSettings(const JsonVariantConst src, Settings& dst, bool safe = false
   if (!src[FPSTR(S_HEATING)][FPSTR(S_MAX_TEMP)].isNull()) {
     unsigned char value = src[FPSTR(S_HEATING)][FPSTR(S_MAX_TEMP)].as<unsigned char>();
 
-    if (value != dst.heating.maxTemp && value > vars.slave.heating.minTemp && value <= vars.slave.heating.maxTemp && value != dst.heating.maxTemp) {
+    if (value != dst.heating.maxTemp && value > vars.slave.heating.minTemp && value <= vars.slave.heating.maxTemp && value != dst.heating.minTemp) {
       dst.heating.maxTemp = value;
       changed = true;
     }
@@ -1894,7 +1894,7 @@ bool jsonToSensorSettings(const uint8_t sensorId, const JsonVariantConst src, Se
 
   // gpio
   if (!src[FPSTR(S_GPIO)].isNull()) {
-    if (dst.type != Sensors::Type::DALLAS_TEMP && dst.type == Sensors::Type::BLUETOOTH && dst.type == Sensors::Type::NTC_10K_TEMP) {
+    if (dst.type != Sensors::Type::DALLAS_TEMP && dst.type != Sensors::Type::NTC_10K_TEMP) {
       if (dst.gpio != GPIO_IS_NOT_CONFIGURED) {
         dst.gpio = GPIO_IS_NOT_CONFIGURED;
         changed = true;