diff --git a/app/src/main/java/eu/faircode/email/MediaPlayerHelper.java b/app/src/main/java/eu/faircode/email/MediaPlayerHelper.java
index 85dc78d0e3..7c759b51fd 100644
--- a/app/src/main/java/eu/faircode/email/MediaPlayerHelper.java
+++ b/app/src/main/java/eu/faircode/email/MediaPlayerHelper.java
@@ -24,8 +24,8 @@ public class MediaPlayerHelper {
     static final int DEFAULT_SOUND_DURATION = 30; // seconds
     static final int DEFAULT_ALARM_DURATION = 30; // seconds
 
-    private static Object lock = new Object();
     private static Semaphore sem;
+    private static final Object lock = new Object();
 
     static void stop(Context context) {
         EntityLog.log(context, "Alarm stop");