diff --git a/lib/crypto/aes.js b/lib/crypto/aes.js
index 26b71215..f7ac9523 100644
--- a/lib/crypto/aes.js
+++ b/lib/crypto/aes.js
@@ -490,7 +490,7 @@ AESCipher.prototype.update = function update(data) {
   var i, len, trailing, block;
 
   if (this.waiting) {
-    data = Buffer.concat([this.waiting, data]);
+    data = concat(this.waiting, data);
     this.waiting = null;
   }
 
@@ -529,7 +529,7 @@ AESCipher.prototype.final = function final() {
     left = 16 - block.length;
     pad = new Buffer(left);
     pad.fill(left);
-    block = Buffer.concat([block, pad]);
+    block = concat(block, pad);
   }
 
   // Encrypt the last block,
@@ -577,7 +577,7 @@ AESDecipher.prototype.update = function update(data) {
   var i, chunk, block, len, trailing;
 
   if (this.waiting) {
-    data = Buffer.concat([this.waiting, data]);
+    data = concat(this.waiting, data);
     this.waiting = null;
   }
 
@@ -656,10 +656,7 @@ AESDecipher.prototype.final = function final() {
 
 AES.encrypt = function encrypt(data, key, iv, bits, mode) {
   var cipher = new AESCipher(key, iv, bits, mode);
-  return Buffer.concat([
-    cipher.update(data),
-    cipher.final()
-  ]);
+  return concat(cipher.update(data), cipher.final());
 };
 
 /**
@@ -674,10 +671,7 @@ AES.encrypt = function encrypt(data, key, iv, bits, mode) {
 
 AES.decrypt = function decrypt(data, key, iv, bits, mode) {
   var decipher = new AESDecipher(key, iv, bits, mode);
-  return Buffer.concat([
-    decipher.update(data),
-    decipher.final()
-  ]);
+  return concat(decipher.update(data), decipher.final());
 };
 
 /**
@@ -771,6 +765,13 @@ function writeU32(data, value, i) {
   data[i + 3] = value & 0xff;
 }
 
+function concat(a, b) {
+  var data = new Buffer(a.length + b.length);
+  a.copy(data, 0);
+  b.copy(data, a.length);
+  return data;
+}
+
 /*
  * Tables
  */
diff --git a/lib/crypto/crypto.js b/lib/crypto/crypto.js
index fece8222..09b6388f 100644
--- a/lib/crypto/crypto.js
+++ b/lib/crypto/crypto.js
@@ -299,10 +299,7 @@ crypto.encipher = function encipher(data, key, iv) {
 
   cipher = nodeCrypto.createCipheriv('aes-256-cbc', key, iv);
 
-  return Buffer.concat([
-    cipher.update(data),
-    cipher.final()
-  ]);
+  return utils.concat(cipher.update(data), cipher.final());
 };
 
 /**
@@ -350,10 +347,7 @@ crypto.decipher = function decipher(data, key, iv) {
 
   decipher = nodeCrypto.createDecipheriv('aes-256-cbc', key, iv);
 
-  return Buffer.concat([
-    decipher.update(data),
-    decipher.final()
-  ]);
+  return utils.concat(decipher.update(data), decipher.final());
 };
 
 /**
diff --git a/lib/script/script.js b/lib/script/script.js
index 1a5cf3f2..45358717 100644
--- a/lib/script/script.js
+++ b/lib/script/script.js
@@ -979,7 +979,7 @@ Script.prototype.execute = function execute(stack, flags, tx, index, version) {
           throw new ScriptError('INVALID_STACK_OPERATION', op, ip);
         v2 = stack.pop();
         v1 = stack.pop();
-        stack.push(Buffer.concat([v1, v2]));
+        stack.push(utils.concat(v1, v2));
         if (stack.top(-1).length > constants.script.MAX_PUSH)
           throw new ScriptError('PUSH_SIZE', op, ip);
         break;
@@ -1035,12 +1035,12 @@ Script.prototype.execute = function execute(stack, flags, tx, index, version) {
         if (v1.length < v2.length) {
           v3 = new Buffer(v2.length - v1.length);
           v3.fill(0);
-          v1 = Buffer.concat([v1, v3]);
+          v1 = utils.concat(v1, v3);
         }
         if (v2.length < v1.length) {
           v3 = new Buffer(v1.length - v2.length);
           v3.fill(0);
-          v2 = Buffer.concat([v2, v3]);
+          v2 = utils.concat(v2, v3);
         }
         if (op === opcodes.OP_AND) {
           for (i = 0; i < v1.length; i++)
diff --git a/lib/utils/utils.js b/lib/utils/utils.js
index 148b2480..07b0ba9c 100644
--- a/lib/utils/utils.js
+++ b/lib/utils/utils.js
@@ -103,6 +103,20 @@ utils.copy = function copy(data) {
   return clone;
 };
 
+/**
+ * Concatenate two buffers.
+ * @param {Buffer} a
+ * @param {Buffer} b
+ * @returns {Buffer}
+ */
+
+utils.concat = function concat(a, b) {
+  var data = new Buffer(a.length + b.length);
+  a.copy(data, 0);
+  b.copy(data, a.length);
+  return data;
+};
+
 /**
  * Encode a base58 string.
  * @see https://github.com/bitcoin/bitcoin/blob/master/src/base58.cpp