diff --git a/lib/services/bitcoind.js b/lib/services/bitcoind.js
index b749c89e..4077c848 100644
--- a/lib/services/bitcoind.js
+++ b/lib/services/bitcoind.js
@@ -111,7 +111,7 @@ Bitcoin.prototype._initCaches = function() {
   this.blockCache = LRU(144);
   this.rawBlockCache = LRU(72);
   this.blockHeaderCache = LRU(288);
-  this.zmqKnownTransactions = LRU(50);
+  this.zmqKnownTransactions = LRU(5000);
   this.zmqKnownBlocks = LRU(50);
   this.lastTip = 0;
   this.lastTipTimeout = false;
@@ -467,7 +467,7 @@ Bitcoin.prototype._updateTip = function(node, message) {
 
 Bitcoin.prototype._zmqTransactionHandler = function(node, message) {
   var self = this;
-  var id = message.toString('binary');
+  var id = bitcore.crypto.Hash.sha256sha256(message).toString('binary');
   if (!self.zmqKnownTransactions.get(id)) {
     self.zmqKnownTransactions.set(id, true);
     self.emit('tx', message);