diff --git a/briar-api/src/net/sf/briar/api/messaging/SubscriptionAck.java b/briar-api/src/net/sf/briar/api/messaging/SubscriptionAck.java
index 5ef2664e9..3a9e79f2c 100644
--- a/briar-api/src/net/sf/briar/api/messaging/SubscriptionAck.java
+++ b/briar-api/src/net/sf/briar/api/messaging/SubscriptionAck.java
@@ -3,7 +3,7 @@ package net.sf.briar.api.messaging;
 /** A packet acknowledging a {@link SubscriptionUpdate}. */
 public class SubscriptionAck {
 
-	final long version;
+	private final long version;
 
 	public SubscriptionAck(long version) {
 		this.version = version;