diff --git a/src/java/com/threerings/presents/client/BlockingCommunicator.java b/src/java/com/threerings/presents/client/BlockingCommunicator.java
index 22d502dd2..6ece46408 100644
--- a/src/java/com/threerings/presents/client/BlockingCommunicator.java
+++ b/src/java/com/threerings/presents/client/BlockingCommunicator.java
@@ -470,7 +470,7 @@ public class BlockingCommunicator extends Communicator
             if (debugLogMessages()) {
                 log.info("RECEIVE " + msg);
             }
-            _client.getMessageTracker().messageReceived(false, size, msg);
+            _client.getMessageTracker().messageReceived(false, size, msg, 0);
             return msg;
 
         } catch (ClassNotFoundException cnfe) {
@@ -496,15 +496,16 @@ public class BlockingCommunicator extends Communicator
         // decode through the sequencer
         try {
             DownstreamMessage msg = (DownstreamMessage)_sequencer.readDatagram();
+            if (_client != null) {
+                _client.getMessageTracker().messageReceived(
+                    true, size, msg, (msg == null) ? 0 : _sequencer.getMissedCount());
+            }
             if (msg == null) {
                 return null; // received out of order
             }
             if (debugLogMessages()) {
                 log.info("DATAGRAM " + msg);
             }
-            if (_client != null) {
-                _client.getMessageTracker().messageReceived(true, size, msg);
-            }
             return msg;
 
         } catch (ClassNotFoundException cnfe) {
diff --git a/src/java/com/threerings/presents/client/MessageTracker.java b/src/java/com/threerings/presents/client/MessageTracker.java
index 8de489a03..310124d36 100644
--- a/src/java/com/threerings/presents/client/MessageTracker.java
+++ b/src/java/com/threerings/presents/client/MessageTracker.java
@@ -36,7 +36,8 @@ public interface MessageTracker
     public static final MessageTracker NOOP = new MessageTracker() {
         public void messageSent (boolean datagram, int size, UpstreamMessage msg) {
         }
-        public void messageReceived (boolean datagram, int size, DownstreamMessage msg) {
+        public void messageReceived (
+            boolean datagram, int size, DownstreamMessage msg, int missed) {
         }
     };
 
@@ -47,6 +48,9 @@ public interface MessageTracker
 
     /**
      * Notes that a message has been received.
+     *
+     * @param msg the received message, or <code>null</code> if received out of order.
+     * @param missed the number of messages missed between this message and the one before it.
      */
-    public void messageReceived (boolean datagram, int size, DownstreamMessage msg);
+    public void messageReceived (boolean datagram, int size, DownstreamMessage msg, int missed);
 }
diff --git a/src/java/com/threerings/presents/util/DatagramSequencer.java b/src/java/com/threerings/presents/util/DatagramSequencer.java
index 0442261bc..c5c1d0349 100644
--- a/src/java/com/threerings/presents/util/DatagramSequencer.java
+++ b/src/java/com/threerings/presents/util/DatagramSequencer.java
@@ -102,6 +102,7 @@ public class DatagramSequencer
         if (number <= _lastReceived) {
             return null;
         }
+        _missedCount = number - _lastReceived - 1;
         _lastReceived = number;
 
         // read the acknowledge number and process all send records up to that one
@@ -132,6 +133,14 @@ public class DatagramSequencer
         return datagram;
     }
 
+    /**
+     * Returns the number of datagrams missed between the last and the one before it.
+     */
+    public int getMissedCount ()
+    {
+        return _missedCount;
+    }
+
     /**
      * A record of a sent datagram.
      */
@@ -168,6 +177,9 @@ public class DatagramSequencer
     /** The most recent sequence number received. */
     protected int _lastReceived;
 
+    /** The number of datagrams missed between the last and the one before it. */
+    protected int _missedCount;
+
     /** Records of datagrams sent. */
     protected ArrayList<SendRecord> _sendrecs = Lists.newArrayList();
 }