diff --git a/src/magic/ui/DelayedViewersThread.java b/src/magic/ui/DelayedViewersThread.java
index 53d128ddd5..ca7daa02cf 100644
--- a/src/magic/ui/DelayedViewersThread.java
+++ b/src/magic/ui/DelayedViewersThread.java
@@ -3,7 +3,7 @@ package magic.ui;
 import java.util.HashMap;
 import java.util.Map;
 
-public class DelayedViewersThread extends Thread {
+public final class DelayedViewersThread extends Thread {
 
 	private static final DelayedViewersThread VIEWER_THREAD=new DelayedViewersThread();