diff --git a/src/modules/rfid/rfid125.cpp b/src/modules/rfid/rfid125.cpp
index 706d1a0eaa..4f9529dd54 100644
--- a/src/modules/rfid/rfid125.cpp
+++ b/src/modules/rfid/rfid125.cpp
@@ -12,6 +12,27 @@
 #include "core/sd_functions.h"
 #include <globals.h>
 
+#define _HEX_DIGIT_ERROR 0xFF
+
+static uint8_t hex2digit(char ch) {
+    if (ch >= '0' && ch <= '9') return ch - '0';
+    if (ch >= 'A' && ch <= 'F') return ch - 'A' + 10;
+    if (ch >= 'a' && ch <= 'f') return ch - 'a' + 10;
+    return _HEX_DIGIT_ERROR;
+}
+
+static uint8_t hex2int(char *ch) {
+    uint8_t lnib, rnib, res;
+    lnib = hex2digit(ch[0]);
+    if (lnib == _HEX_DIGIT_ERROR) return _HEX_DIGIT_ERROR;
+
+    rnib = hex2digit(ch[1]);
+    if (rnib == _HEX_DIGIT_ERROR) return _HEX_DIGIT_ERROR;
+
+    res = ((lnib << 4) | 0x0F) & (rnib | 0xF0);
+    return res;
+}
+
 RFID125::RFID125() {
     _initial_state = READ_MODE;
     setup();
@@ -171,8 +192,7 @@ void RFID125::read_card() {
 
 bool RFID125::read_card_data() {
     char buff[RFID125_PACKET_SIZE];
-    uint8_t checksum;
-    uint32_t tag_id;
+    uint8_t checksum, check;
 
     if (!_stream) return false;
 
@@ -189,21 +209,19 @@ bool RFID125::read_card_data() {
 
     for (int i = 0; i < RFID125_PACKET_SIZE; i++) _tag_data[i] = buff[i];
 
-    /* add null and parse checksum */
-    buff[13] = 0;
-    checksum = strtol(buff + 11, NULL, 16);
-    /* add null and parse tag_id */
-    buff[11] = 0;
-    tag_id = strtol(buff + 3, NULL, 16);
-    /* add null and parse version (needs to be xored with checksum) */
-    buff[3] = 0;
-    checksum ^= strtol(buff + 1, NULL, 16);
+    /* We read the provided checksum integer read from UART*/
+    checksum = hex2int(buff + 11);
+    if (checksum == _HEX_DIGIT_ERROR) return false;
 
-    /* xore the tag_id and validate checksum */
-    for (uint8_t i = 0; i < 32; i += 8) checksum ^= ((tag_id >> i) & 0xFF);
-    if (checksum) return false;
+    /* We compute xor check on payload data */
+    check = hex2int(&buff[1]);
+    if (check == _HEX_DIGIT_ERROR) return false;
 
-    return true;
+    for (int i = 3; i < 11; i += 2) {
+        uint8_t value = hex2int(buff + i);
+        check ^= value;
+    }
+    return check == checksum;
 }
 
 void RFID125::clear_stream() {