diff --git a/src/as/com/threerings/presents/client/InvocationDirector.as b/src/as/com/threerings/presents/client/InvocationDirector.as
index fde42a304..85ffde1cc 100644
--- a/src/as/com/threerings/presents/client/InvocationDirector.as
+++ b/src/as/com/threerings/presents/client/InvocationDirector.as
@@ -190,7 +190,6 @@ public class InvocationDirector
             if (arg is InvocationMarshaller_ListenerMarshaller) {
                 var lm :InvocationMarshaller_ListenerMarshaller =
                     (arg as InvocationMarshaller_ListenerMarshaller);
-                lm.callerOid = _clobj.getOid();
                 lm.requestId = nextRequestId();
                 lm.mapStamp = getTimer();
 
diff --git a/src/as/com/threerings/presents/data/InvocationMarshaller_ListenerMarshaller.as b/src/as/com/threerings/presents/data/InvocationMarshaller_ListenerMarshaller.as
index 8c567fe4d..d6429ad01 100644
--- a/src/as/com/threerings/presents/data/InvocationMarshaller_ListenerMarshaller.as
+++ b/src/as/com/threerings/presents/data/InvocationMarshaller_ListenerMarshaller.as
@@ -36,9 +36,6 @@ public class InvocationMarshaller_ListenerMarshaller
     /** The method id used to dispatch a requestFailed response. */
     public static const REQUEST_FAILED_RSPID :int = 0;
 
-    /** The oid of the invocation service requester. */
-    public var callerOid :int;
-
     /** The request id associated with this listener. */
     public var requestId :int;
 
@@ -70,14 +67,12 @@ public class InvocationMarshaller_ListenerMarshaller
      */
     public function toString () :String
     {
-        return "[callerOid=" + callerOid + ", reqId=" + requestId +
-            ", type=" + ClassUtil.getClassName(this) +  "]";
+        return "[reqId=" + requestId + ", type=" + ClassUtil.getClassName(this) +  "]";
     }
 
     // documentation inherited from interface Streamable
     public function writeObject (out :ObjectOutputStream) :void
     {
-        out.writeInt(callerOid);
         out.writeShort(requestId);
     }
 
diff --git a/src/java/com/threerings/presents/client/InvocationDirector.java b/src/java/com/threerings/presents/client/InvocationDirector.java
index e0211a426..97ac511ff 100644
--- a/src/java/com/threerings/presents/client/InvocationDirector.java
+++ b/src/java/com/threerings/presents/client/InvocationDirector.java
@@ -218,7 +218,6 @@ public class InvocationDirector
             Object arg = args[ii];
             if (arg instanceof ListenerMarshaller) {
                 ListenerMarshaller lm = (ListenerMarshaller)arg;
-                lm.callerOid = _clobj.getOid();
                 lm.requestId = nextRequestId();
                 lm.mapStamp = System.currentTimeMillis();
                 // create a mapping for this marshaller so that we can properly dispatch responses
diff --git a/src/java/com/threerings/presents/data/InvocationMarshaller.java b/src/java/com/threerings/presents/data/InvocationMarshaller.java
index f9eafe3e6..f0927ff5b 100644
--- a/src/java/com/threerings/presents/data/InvocationMarshaller.java
+++ b/src/java/com/threerings/presents/data/InvocationMarshaller.java
@@ -47,12 +47,12 @@ public class InvocationMarshaller
         /** The method id used to dispatch a {@link #requestFailed} response. */
         public static final int REQUEST_FAILED_RSPID = 0;
 
-        /** The oid of the invocation service requester. */
-        public int callerOid;
-
         /** The request id associated with this listener. */
         public short requestId;
 
+        /** The oid of the invocation service requester. Only used on the server. */
+        public transient int callerOid;
+
         /** The actual invocation listener associated with this marshalling listener. This is only
          * valid on the client. */
         public transient InvocationListener listener;
diff --git a/src/java/com/threerings/presents/server/InvocationManager.java b/src/java/com/threerings/presents/server/InvocationManager.java
index dd0963187..a2f6af0e9 100644
--- a/src/java/com/threerings/presents/server/InvocationManager.java
+++ b/src/java/com/threerings/presents/server/InvocationManager.java
@@ -245,6 +245,7 @@ public class InvocationManager
             Object arg = args[ii];
             if (arg instanceof ListenerMarshaller) {
                 ListenerMarshaller list = (ListenerMarshaller)arg;
+                list.callerOid = clientOid;
                 list.omgr = _omgr;
                 list.transport = transport;
                 // keep track of the listener we'll inform if anything