diff --git a/android/app/src/main/java/com/eddy/atomrelay/MainActivity.kt b/android/app/src/main/java/com/eddy/atomrelay/MainActivity.kt
index d83c695..9af284c 100644
--- a/android/app/src/main/java/com/eddy/atomrelay/MainActivity.kt
+++ b/android/app/src/main/java/com/eddy/atomrelay/MainActivity.kt
@@ -166,14 +166,14 @@ class MainActivity : AppCompatActivity() {
             bluetoothGatt = null
             relayCharacteristic = null
             seq = 1
-            loadHmacKey()
+            loadState()
             handler.postDelayed(scanRunnable, 500)
         }
     }
 
     override fun onResume() {
         super.onResume()
-        loadHmacKey()
+        loadState()
         if (hmacKey == null) {
             statusText.text = "Geen HMAC sleutel - open Instellingen"
         } else if (!isScanning && bluetoothGatt == null) {
@@ -187,11 +187,12 @@ class MainActivity : AppCompatActivity() {
         stopScan()
     }
 
-    private fun loadHmacKey() {
+    private fun loadState() {
         val prefs = PrefsHelper.getPrefs(this)
         val hexKey = prefs.getString(PrefsHelper.PREF_KEY, null)
         hmacKey = hexKey?.let { hexStringToBytes(it) }
-        Log.d(TAG, "HMAC key loaded: ${if (hmacKey != null) "${hmacKey!!.size} bytes" else "none"}")
+        seq = prefs.getInt(PrefsHelper.PREF_SEQ, 1).coerceAtMost(PrefsHelper.SEQ_MAX)
+        Log.d(TAG, "HMAC key loaded: ${if (hmacKey != null) "${hmacKey!!.size} bytes" else "none"}, seq=$seq")
     }
 
     private fun hexStringToBytes(hex: String): ByteArray? {
@@ -314,6 +315,8 @@ class MainActivity : AppCompatActivity() {
         char.writeType = BluetoothGattCharacteristic.WRITE_TYPE_NO_RESPONSE
         gatt.writeCharacteristic(char)
         seq++
+        if (seq > PrefsHelper.SEQ_MAX) seq = 1
+        PrefsHelper.getPrefs(this).edit().putInt(PrefsHelper.PREF_SEQ, seq).apply()
         Log.d(TAG, "Sent relay ${if (on) "ON" else "OFF"} (seq=${seq - 1})")
     }
 
diff --git a/android/app/src/main/java/com/eddy/atomrelay/PrefsHelper.kt b/android/app/src/main/java/com/eddy/atomrelay/PrefsHelper.kt
index 2eff494..f17480e 100644
--- a/android/app/src/main/java/com/eddy/atomrelay/PrefsHelper.kt
+++ b/android/app/src/main/java/com/eddy/atomrelay/PrefsHelper.kt
@@ -12,6 +12,8 @@ object PrefsHelper {
     private const val TAG = "PrefsHelper"
     const val PREFS_NAME = "relay_prefs"
     const val PREF_KEY = "hmac_key"
+    const val PREF_SEQ = "seq_counter"
+    const val SEQ_MAX = 1_000_000
 
     fun getPrefs(context: Context): SharedPreferences {
         return try {