diff --git a/src/ax25_utils.cpp b/src/ax25_utils.cpp
index 099ba9a..7aa3c6d 100644
--- a/src/ax25_utils.cpp
+++ b/src/ax25_utils.cpp
@@ -81,7 +81,7 @@ namespace AX25_Utils {
         return frame;
     }
 
-    std::string intToBinaryString(uint8_t value, uint8_t bitLength) {
+    std::string intToBinaryString(uint8_t value, const uint8_t bitLength) {
         std::string result = "";
         //result.reserve(bitLength);
         for (int i = bitLength - 1; i >= 0; i--) {
@@ -90,7 +90,7 @@ namespace AX25_Utils {
         return result;
     }
 
-    String encodeAX25Address(const String& frame, uint8_t type, bool lastAddress) {
+    String encodeAX25Address(const String& frame, uint8_t type, const bool lastAddress) {
         String packet = "";
         String address;
         std::string concatenatedBinary;
diff --git a/src/ax25_utils.h b/src/ax25_utils.h
index 78ac38a..dfcf864 100644
--- a/src/ax25_utils.h
+++ b/src/ax25_utils.h
@@ -39,8 +39,8 @@ namespace AX25_Utils {
     bool            decodeAX25(const String& frame, int frameSize, AX25Frame* decodedFrame);
     String          AX25FrameToLoRaPacket(const String& frame);
     String          frameCleaning(const String& frameToClean);
-    std::string     intToBinaryString(uint8_t value, uint8_t bitLength);
-    String          encodeAX25Address(const String& frame, uint8_t type, bool lastAddress);
+    std::string     intToBinaryString(uint8_t value, const uint8_t bitLength);
+    String          encodeAX25Address(const String& frame, uint8_t type, const bool lastAddress);
     String          LoRaPacketToAX25Frame(const String& packet);
 
 }
diff --git a/src/menu_utils.cpp b/src/menu_utils.cpp
index 7f7fa85..c7b3de1 100644
--- a/src/menu_utils.cpp
+++ b/src/menu_utils.cpp
@@ -49,7 +49,7 @@ uint8_t     lowBatteryPercent       = 21;
 
 namespace MENU_Utils {
 
-    String checkBTType() {
+    const String checkBTType() {
         switch (Config.bluetoothType) {
             case 0:
                 return "BLE iPhone";
@@ -62,7 +62,7 @@ namespace MENU_Utils {
         }
     }
 
-    String checkProcessActive(bool process) {
+    const String checkProcessActive(const bool process) {
         if (process) {
             return "ON";
         } else {
diff --git a/src/menu_utils.h b/src/menu_utils.h
index 4faaa94..6bad6e6 100644
--- a/src/menu_utils.h
+++ b/src/menu_utils.h
@@ -5,10 +5,10 @@
 
 namespace MENU_Utils {
     
-    String  checkBTType();
-    String  checkProcessActive(bool process);
+    const String checkBTType();
+    const String checkProcessActive(const bool process);
     const String screenBrightnessAsString(const uint8_t bright);
-    void    showOnScreen();
+    void  showOnScreen();
 
 }
 
diff --git a/src/msg_utils.cpp b/src/msg_utils.cpp
index 2414266..53478fa 100644
--- a/src/msg_utils.cpp
+++ b/src/msg_utils.cpp
@@ -68,7 +68,7 @@ namespace MSG_Utils {
         return noWLNKMsgWarning;
     }
 
-    String getLastHeardTracker() {
+    const String getLastHeardTracker() {
         return lastHeardTracker;
     }
 
@@ -256,7 +256,7 @@ namespace MSG_Utils {
         LoRa_Utils::sendNewPacket(newPacket);
     }
 
-    String ackRequestNumberGenerator() {
+    const String ackRequestNumberGenerator() {
         ackRequestNumber++;
         if (ackRequestNumber > 999) {
             ackRequestNumber = 1;
diff --git a/src/msg_utils.h b/src/msg_utils.h
index 529b115..730b75d 100644
--- a/src/msg_utils.h
+++ b/src/msg_utils.h
@@ -8,7 +8,7 @@ namespace MSG_Utils {
 
     bool    warnNoAPRSMessages();
     bool    warnNoWLNKMails();
-    String  getLastHeardTracker();
+    const String getLastHeardTracker();
     int     getNumAPRSMessages();
     int     getNumWLNKMails();
     void    loadNumMessages();
@@ -17,7 +17,7 @@ namespace MSG_Utils {
     void    deleteFile(uint8_t typeOfFile);
     void    saveNewMessage(uint8_t typeMessage, const String& station, const String& newMessage);
     void    sendMessage(const String& station, const String& textMessage);
-    String  ackRequestNumberGenerator();
+    const String ackRequestNumberGenerator();
     void    addToOutputBuffer(uint8_t typeOfMessage, const String& station, const String& textMessage);
     void    processOutputBuffer();
     void    clean25SegBuffer();
diff --git a/src/power_utils.cpp b/src/power_utils.cpp
index c8aad98..700522c 100644
--- a/src/power_utils.cpp
+++ b/src/power_utils.cpp
@@ -86,11 +86,11 @@ namespace POWER_Utils {
     #endif    
     }
 
-    String getBatteryInfoVoltage() {
+    const String getBatteryInfoVoltage() {
         return batteryVoltage;
     }
 
-    String getBatteryInfoCurrent() {
+    const String getBatteryInfoCurrent() {
         return batteryChargeDischargeCurrent;
     }
 
diff --git a/src/power_utils.h b/src/power_utils.h
index a6b0990..0231f4c 100644
--- a/src/power_utils.h
+++ b/src/power_utils.h
@@ -11,8 +11,8 @@
 namespace POWER_Utils {
 
     double  getBatteryVoltage();
-    String  getBatteryInfoVoltage();
-    String  getBatteryInfoCurrent();
+    const String getBatteryInfoVoltage();
+    const String getBatteryInfoCurrent();
     bool    getBatteryInfoIsConnected();
 
     void    enableChgLed();
diff --git a/src/station_utils.cpp b/src/station_utils.cpp
index 5d5cdab..40f0882 100644
--- a/src/station_utils.cpp
+++ b/src/station_utils.cpp
@@ -56,19 +56,19 @@ uint32_t    lastDeleteListenedTracker;
 
 namespace STATION_Utils {
 
-    String getFirstNearTracker() {
+    const String getFirstNearTracker() {
         return String(firstNearTracker.substring(0, firstNearTracker.indexOf(",")));
     }
 
-    String getSecondNearTracker() {
+    const String getSecondNearTracker() {
         return String(secondNearTracker.substring(0, secondNearTracker.indexOf(",")));
     }
 
-    String getThirdNearTracker() {
+    const String getThirdNearTracker() {
         return String(thirdNearTracker.substring(0, thirdNearTracker.indexOf(",")));
     }
 
-    String getFourthNearTracker() {
+    const String getFourthNearTracker() {
         return String(fourthNearTracker.substring(0, fourthNearTracker.indexOf(",")));
     }
 
diff --git a/src/station_utils.h b/src/station_utils.h
index de519a6..fe041c0 100644
--- a/src/station_utils.h
+++ b/src/station_utils.h
@@ -5,10 +5,10 @@
 
 namespace STATION_Utils {
 
-    String  getFirstNearTracker();
-    String  getSecondNearTracker();
-    String  getThirdNearTracker();
-    String  getFourthNearTracker();
+    const String getFirstNearTracker();
+    const String getSecondNearTracker();
+    const String getThirdNearTracker();
+    const String getFourthNearTracker();
 
     void    deleteListenedTrackersbyTime();
     void    checkListenedTrackersByTimeAndDelete();