diff --git a/bin/spvnode b/bin/spvnode
index f9a2f2f6..b02d4687 100755
--- a/bin/spvnode
+++ b/bin/spvnode
@@ -25,8 +25,11 @@ node.open(function(err) {
 
   if (process.argv.indexOf('--test') !== -1) {
     node.pool.watchAddress('1VayNert3x1KzbpzMGt2qdqrAThiRovi8');
-    node.on('tx', function(tx) {
-      utils.log(tx);
+    node.pool.watch(bcoin.outpoint().toRaw());
+    node.on('block', function(block) {
+      assert(block.txs.length >= 1);
+      if (block.txs.length > 1)
+        utils.log(block.txs[1]);
     });
   }
 
diff --git a/lib/bcoin/crypto.js b/lib/bcoin/crypto.js
index 183d7315..50f4f172 100644
--- a/lib/bcoin/crypto.js
+++ b/lib/bcoin/crypto.js
@@ -429,17 +429,26 @@ crypto.ccmp = function ccmp(a, b) {
 crypto.buildMerkleTree = function buildMerkleTree(leaves) {
   var tree = leaves.slice();
   var size = leaves.length;
-  var i, j, i2, hash;
+  var i, j, i2, hash, left, right, buf;
+
+  if (size > 1)
+    buf = new Buffer(64);
 
   for (j = 0; size > 1; size = ((size + 1) / 2) | 0) {
     for (i = 0; i < size; i += 2) {
       i2 = Math.min(i + 1, size - 1);
+      left = tree[j + i];
+      right = tree[j + i2];
+
       if (i2 === i + 1 && i2 + 1 === size
-          && tree[j + i].compare(tree[j + i2]) === 0) {
+          && left.compare(right) === 0) {
         return;
       }
-      hash = Buffer.concat([tree[j + i], tree[j + i2]]);
-      hash = crypto.hash256(hash);
+
+      left.copy(buf, 0);
+      right.copy(buf, 32);
+      hash = crypto.hash256(buf);
+
       tree.push(hash);
     }
     j += size;
@@ -498,19 +507,25 @@ crypto.getMerkleBranch = function getMerkleBranch(index, leaves) {
  */
 
 crypto.checkMerkleBranch = function checkMerkleBranch(hash, branch, index) {
-  var otherside, i;
+  var i, otherside, buf;
 
-  if (index === -1)
-    return false;
+  if (branch.length === 0)
+    return hash;
+
+  buf = new Buffer(64);
 
   for (i = 0; i < branch.length; i++) {
     otherside = branch[i];
 
-    if (index & 1)
-      hash = crypto.hash256(Buffer.concat([otherside, hash]));
-    else
-      hash = crypto.hash256(Buffer.concat([hash, otherside]));
+    if (index & 1) {
+      otherside.copy(buf, 0);
+      hash.copy(buf, 32);
+    } else {
+      hash.copy(buf, 0);
+      otherside.copy(buf, 32);
+    }
 
+    hash = crypto.hash256(buf);
     index >>>= 1;
   }
 
diff --git a/lib/bcoin/merkleblock.js b/lib/bcoin/merkleblock.js
index 7105e27d..8720a201 100644
--- a/lib/bcoin/merkleblock.js
+++ b/lib/bcoin/merkleblock.js
@@ -162,7 +162,7 @@ MerkleBlock.prototype.extractTree = function extractTree() {
   var flags = this.flags;
   var totalTX = this.totalTX;
   var height = 0;
-  var root, p;
+  var root, p, buf;
 
   function width(height) {
     return (totalTX + (1 << height) - 1) >>> height;
@@ -203,7 +203,10 @@ MerkleBlock.prototype.extractTree = function extractTree() {
       right = left;
     }
 
-    return utils.hash256(Buffer.concat([left, right]));
+    left.copy(buf, 0);
+    right.copy(buf, 32);
+
+    return utils.hash256(buf);
   }
 
   for (p = 0; p < this.hashes.length; p++)
@@ -225,6 +228,9 @@ MerkleBlock.prototype.extractTree = function extractTree() {
   while (width(height) > 1)
     height++;
 
+  if (height > 0)
+    buf = new Buffer(64);
+
   root = traverse(height, 0);
 
   if (failed)
@@ -446,7 +452,7 @@ MerkleBlock.fromBlock = function fromBlock(block, filter) {
   var leaves = [];
   var bits = [];
   var hashes = [];
-  var i, tx, totalTX, height, flags, p, merkle;
+  var i, tx, totalTX, height, flags, p, merkle, buf;
 
   for (i = 0; i < block.txs.length; i++) {
     tx = block.txs[i];
@@ -478,7 +484,10 @@ MerkleBlock.fromBlock = function fromBlock(block, filter) {
     else
       right = left;
 
-    return utils.hash256(Buffer.concat([left, right]));
+    left.copy(buf, 0);
+    right.copy(buf, 32);
+
+    return utils.hash256(buf);
   }
 
   function traverse(height, pos, leaves, matches) {
@@ -505,6 +514,9 @@ MerkleBlock.fromBlock = function fromBlock(block, filter) {
   while (width(height) > 1)
     height++;
 
+  if (height > 0)
+    buf = new Buffer(64);
+
   traverse(height, 0, leaves, matches);
 
   flags = new Buffer((bits.length + 7) / 8 | 0);