diff --git a/Firmware/RTK_Everywhere/Device_Update.h b/Firmware/RTK_Everywhere/Device_Update.h
index b37c31b16..c9c79d9c6 100644
--- a/Firmware/RTK_Everywhere/Device_Update.h
+++ b/Firmware/RTK_Everywhere/Device_Update.h
@@ -194,7 +194,7 @@ typedef void (* DEVICE_CLOSE)(DEVICE_FIRMWARE_CTX * ctx);
 typedef bool (* DEVICE_OPEN)(DEVICE_FIRMWARE_CTX * ctx);
 typedef bool (* DEVICE_RESET)(DEVICE_FIRMWARE_CTX * ctx, uint32_t currentMsec);
 typedef ssize_t (* DEVICE_WRITE)(DEVICE_FIRMWARE_CTX * ctx,
-                                 uint8_t * buffer,
+                                 const uint8_t * buffer,
                                  size_t bytesToWrite);
 typedef String (* GET_FIRMWARE_VERSION)(DEVICE_FIRMWARE_CTX * ctx);
 typedef bool (* INIT_DEV_CTX)(DEVICE_FIRMWARE_CTX * ctx);
@@ -301,10 +301,10 @@ bool dfuLg290pOpen(DEVICE_FIRMWARE_CTX * ctx);
 
 // Device write, perform the firmware update
 ssize_t dfuEsp32Write(DEVICE_FIRMWARE_CTX * ctx,
-                      uint8_t * buffer,
+                      const uint8_t * buffer,
                       size_t bytesToWrite);
 ssize_t dfuLg290pWrite(DEVICE_FIRMWARE_CTX * ctx,
-                       uint8_t * buffer,
+                       const uint8_t * buffer,
                        size_t bytesToWrite);
 
 // Device close, finalize the firmware update
diff --git a/Firmware/RTK_Everywhere/Device_Update_ESP32.ino b/Firmware/RTK_Everywhere/Device_Update_ESP32.ino
index dd2c0bf95..932cae615 100644
--- a/Firmware/RTK_Everywhere/Device_Update_ESP32.ino
+++ b/Firmware/RTK_Everywhere/Device_Update_ESP32.ino
@@ -97,8 +97,8 @@ void dfuEsp32Reboot()
 // ESP32 firmware write
 //----------------------------------------
 ssize_t dfuEsp32Write(DEVICE_FIRMWARE_CTX * ctx,
-                   uint8_t * buffer,
+                   const uint8_t * buffer,
                    size_t bytesToWrite)
 {
-    return Update.write(buffer, bytesToWrite);
+    return Update.write((uint8_t *)buffer, bytesToWrite);
 }
diff --git a/Firmware/RTK_Everywhere/Device_Update_LG290P.ino b/Firmware/RTK_Everywhere/Device_Update_LG290P.ino
index 8fac7bed2..f6e8133d8 100644
--- a/Firmware/RTK_Everywhere/Device_Update_LG290P.ino
+++ b/Firmware/RTK_Everywhere/Device_Update_LG290P.ino
@@ -431,7 +431,7 @@ bool dfuLg290pReset()
 // LG290P firmware write
 //----------------------------------------
 ssize_t dfuLg290pWrite(DEVICE_FIRMWARE_CTX * ctx,
-                       uint8_t * buffer,
+                       const uint8_t * buffer,
                        size_t bytesToWrite)
 {
     size_t commandLength;
diff --git a/Firmware/RTK_Everywhere/Device_Update_NVM.ino b/Firmware/RTK_Everywhere/Device_Update_NVM.ino
index 98c15db27..3d0394d16 100644
--- a/Firmware/RTK_Everywhere/Device_Update_NVM.ino
+++ b/Firmware/RTK_Everywhere/Device_Update_NVM.ino
@@ -191,7 +191,7 @@ ssize_t dfuNvmRead(DEVICE_FIRMWARE_CTX * ctx,
 // Write firmware data to an NVM file
 //----------------------------------------
 ssize_t dfuNvmWrite(DEVICE_FIRMWARE_CTX * ctx,
-                    uint8_t * buffer,
+                    const uint8_t * buffer,
                     size_t bytesToWrite)
 {
     return ctx->_nvmFile.write(buffer, bytesToWrite);
diff --git a/Firmware/RTK_Everywhere/Device_Update_SD.ino b/Firmware/RTK_Everywhere/Device_Update_SD.ino
index fab6f92ea..640c95f89 100644
--- a/Firmware/RTK_Everywhere/Device_Update_SD.ino
+++ b/Firmware/RTK_Everywhere/Device_Update_SD.ino
@@ -161,7 +161,7 @@ ssize_t dfuSdRead(DEVICE_FIRMWARE_CTX * ctx,
 // Copy firmware into the file
 //----------------------------------------
 ssize_t dfuSdWrite(DEVICE_FIRMWARE_CTX * ctx,
-                   uint8_t * buffer,
+                   const uint8_t * buffer,
                    size_t bytesToWrite)
 {
     return ctx->_sdFile.write(buffer, bytesToWrite);