diff --git a/src/A7670_utils.cpp b/src/A7670_utils.cpp
index a9eb0d9f..604a715f 100644
--- a/src/A7670_utils.cpp
+++ b/src/A7670_utils.cpp
@@ -83,7 +83,7 @@
             }
         }
 
-        bool checkATResponse(String ATMessage) {
+        bool checkATResponse(const String& ATMessage) {
             int delayATMessage = 3000;
             bool validAT = false;
             //Serial.println(ATMessage);
@@ -170,7 +170,7 @@
             }
         }
 
-        void uploadToAPRSIS(String packet) {
+        void uploadToAPRSIS(const String& packet) {
             beaconBytesSended = checkATResponse("AT+CIPSEND=0," + String(packet.length()+1));
             delay(2000);
             if (beaconBytesSended) {
diff --git a/src/A7670_utils.h b/src/A7670_utils.h
index d61eea01..5c28afc3 100644
--- a/src/A7670_utils.h
+++ b/src/A7670_utils.h
@@ -7,9 +7,9 @@ namespace A7670_Utils {
 
     bool checkModemOn();
     void setup();
-    bool checkATResponse(String ATMessage);
+    bool checkATResponse(const String& ATMessage);
     void APRS_IS_connect();
-    void uploadToAPRSIS(String packet);
+    void uploadToAPRSIS(const String& packet);
     void listenAPRSIS();
 
 }