diff --git a/mqlib.js b/mqlib.js
index b25ff78..8b2e164 100644
--- a/mqlib.js
+++ b/mqlib.js
@@ -457,7 +457,7 @@ var sMsgCache = {
           for (var a in aWait)
             return aRead(a);
         } else {
-          sMsgCache.put(iId, data);
+          sMsgCache._put(iId, data);
           for (var a in aWait)
             aWait[a](data);
         }
@@ -467,13 +467,16 @@ var sMsgCache = {
     aRead(iNode);
   } ,
 
-  put: function(iId, iMsg) {
+  add: function(iId, iMsg) {
+    if (iId in this.cache) throw new Error('item already in cache');
+    this.cache[iId] = { count:0, msg:null };
+    this._put(iId, iMsg);
+  } ,
+
+  _put: function(iId, iMsg) {
     if (iMsg.length > sMsgCacheMax/10)
       return;
-    if (iId in this.cache)
-      this.cache[iId].msg = iMsg;
-    else
-      this.cache[iId] = { count:0, msg:iMsg };
+    this.cache[iId].msg = iMsg;
     this.list.append(this.cache[iId]);
     this.size += iMsg.length;
     if (this.size > sMsgCacheMax)
@@ -737,7 +740,7 @@ Link.prototype = {
         fs.fsync(fd, function(err) {
           fs.close(fd, noop);
           if (err) return that._ackFail(iReq.id, err, iOp);
-          sMsgCache.put(aId, aMsg);
+          sMsgCache.add(aId, aMsg);
           var aTo = {}, aToCount = 0;
           for (var aUid in iReq.to) {
             ++aToCount;
@@ -765,8 +768,10 @@ Link.prototype = {
               ++aToCount;
               queueItem(aN, aId, aTo[aN], fToCb);
             }
-            if (aToCount === 0)
+            if (aToCount === 0) {
+              sMsgCache.unlink(aId);
               fToCb();
+            }
             function fToCb() {
               if (--aToCount > 0)
                 return;