diff --git a/data/settings.html b/data/settings.html
index a5081ab..4bf88c3 100644
--- a/data/settings.html
+++ b/data/settings.html
@@ -241,7 +241,7 @@
             </label>
             <label for="indoor-sensor-ble-addresss">
               BLE addresss
-              <input type="text" class="indoor-sensor-ble-addresss" name="sensors[indoor][bleAddresss]" maxlength="17">
+              <input type="text" class="indoor-sensor-ble-addresss" name="sensors[indoor][bleAddresss]" pattern="([A-Fa-f0-9]{2}:){5}[A-Fa-f0-9]{2}">
               <small>ONLY for some ESP32 which support BLE</small>
             </label>
           </div>
diff --git a/src/Settings.h b/src/Settings.h
index 783da7f..a298e93 100644
--- a/src/Settings.h
+++ b/src/Settings.h
@@ -110,7 +110,7 @@ struct Settings {
       // 1 - manual, 2 - ds18b20, 3 - ble
       byte type = 1;
       byte pin = SENSOR_INDOOR_PIN_DEFAULT;
-      char bleAddresss[18];
+      char bleAddresss[18] = "00:00:00:00:00:00";
       float offset = 0.0f;
     } indoor;
   } sensors;