diff --git a/tasmota/xdrv_79_esp32_ble.ino b/tasmota/xdrv_79_esp32_ble.ino
index c9586a45e..5775c3016 100644
--- a/tasmota/xdrv_79_esp32_ble.ino
+++ b/tasmota/xdrv_79_esp32_ble.ino
@@ -1015,6 +1015,18 @@ int fromHex(uint8_t *dest, const char *src, int maxlen){
     t[0] = src[i*2];
     t[1] = src[i*2 + 1];
     t[2] = 0;
+    t[0] |= 0x20;
+    t[1] |= 0x20;
+    if (isalpha(t[0])){
+      if (t[0] < 'a' || t[0] > 'f'){
+        return 0;
+      }
+    }
+    if (isalpha(t[1])){
+      if (t[1] < 'a' || t[1] > 'f'){
+        return 0;
+      }
+    }
 
     int byte = strtol(t, NULL, 16);
     *dest++ = byte;