diff --git a/lib/hd/private.js b/lib/hd/private.js
index b9632209..c1898b47 100644
--- a/lib/hd/private.js
+++ b/lib/hd/private.js
@@ -7,6 +7,7 @@
 'use strict';
 
 var utils = require('../utils/utils');
+var LRU = require('../utils/lru');
 var crypto = require('../crypto/crypto');
 var ec = require('../crypto/ec');
 var assert = require('assert');
@@ -187,11 +188,19 @@ HDPrivateKey.prototype.destroy = function destroy(pub) {
  * @returns {HDPrivateKey}
  */
 
-HDPrivateKey.prototype.derive = function derive(index, hardened) {
+HDPrivateKey.prototype.derive = function derive(index, hardened, cache) {
   var p, id, data, hash, left, right, key, child;
 
+  if (hardened instanceof LRU) {
+    cache = hardened;
+    hardened = false;
+  }
+
+  if (!cache)
+    cache = HD.cache;
+
   if (typeof index === 'string')
-    return this.derivePath(index);
+    return this.derivePath(index, cache);
 
   hardened = index >= constants.hd.HARDENED ? true : hardened;
 
@@ -204,11 +213,12 @@ HDPrivateKey.prototype.derive = function derive(index, hardened) {
   if (this.depth >= 0xff)
     throw new Error('Depth too high.');
 
-  id = this.getID(index);
-  child = HD.cache.get(id);
-
-  if (child)
-    return child;
+  if (cache) {
+    id = this.getID(index);
+    child = cache.get(id);
+    if (child)
+      return child;
+  }
 
   p = new BufferWriter();
 
@@ -245,7 +255,8 @@ HDPrivateKey.prototype.derive = function derive(index, hardened) {
   child.privateKey = key;
   child.publicKey = ec.publicKeyCreate(key, true);
 
-  HD.cache.set(id, child);
+  if (cache)
+    cache.set(id, child);
 
   return child;
 };
@@ -270,13 +281,13 @@ HDPrivateKey.prototype.getID = function getID(index) {
  * @throws Error if key is not a master key.
  */
 
-HDPrivateKey.prototype.deriveAccount44 = function deriveAccount44(accountIndex) {
+HDPrivateKey.prototype.deriveAccount44 = function deriveAccount44(accountIndex, cache) {
   assert(utils.isNumber(accountIndex), 'Account index must be a number.');
   assert(this.isMaster(), 'Cannot derive account index.');
   return this
-    .derive(44, true)
-    .derive(this.network.keyPrefix.coinType, true)
-    .derive(accountIndex, true);
+    .derive(44, true, cache)
+    .derive(this.network.keyPrefix.coinType, true, cache)
+    .derive(accountIndex, true, cache);
 };
 
 /**
@@ -284,9 +295,9 @@ HDPrivateKey.prototype.deriveAccount44 = function deriveAccount44(accountIndex)
  * @returns {HDPrivateKey}
  */
 
-HDPrivateKey.prototype.derivePurpose45 = function derivePurpose45() {
+HDPrivateKey.prototype.derivePurpose45 = function derivePurpose45(cache) {
   assert(this.isMaster(), 'Cannot derive purpose 45.');
-  return this.derive(45, true);
+  return this.derive(45, true, cache);
 };
 
 /**
@@ -395,13 +406,13 @@ HDPrivateKey.isValidPath = function isValidPath(path) {
  * @throws Error if `path` is not a valid path.
  */
 
-HDPrivateKey.prototype.derivePath = function derivePath(path) {
+HDPrivateKey.prototype.derivePath = function derivePath(path, cache) {
   var indexes = HD.parsePath(path, constants.hd.MAX_INDEX);
   var key = this;
   var i;
 
   for (i = 0; i < indexes.length; i++)
-    key = key.derive(indexes[i]);
+    key = key.derive(indexes[i], cache);
 
   return key;
 };
diff --git a/lib/hd/public.js b/lib/hd/public.js
index 171adadb..f722f9e2 100644
--- a/lib/hd/public.js
+++ b/lib/hd/public.js
@@ -7,6 +7,7 @@
 'use strict';
 
 var utils = require('../utils/utils');
+var LRU = require('../utils/lru');
 var crypto = require('../crypto/crypto');
 var ec = require('../crypto/ec');
 var assert = require('assert');
@@ -140,11 +141,19 @@ HDPublicKey.prototype.destroy = function destroy() {
  * @throws on `hardened`
  */
 
-HDPublicKey.prototype.derive = function derive(index, hardened) {
+HDPublicKey.prototype.derive = function derive(index, hardened, cache) {
   var p, id, data, hash, left, right, key, child;
 
+  if (hardened instanceof LRU) {
+    cache = hardened;
+    hardened = false;
+  }
+
+  if (!cache)
+    cache = HD.cache;
+
   if (typeof index === 'string')
-    return this.derivePath(index);
+    return this.derivePath(index, cache);
 
   if (index >= constants.hd.HARDENED || hardened)
     throw new Error('Index out of range.');
@@ -155,11 +164,12 @@ HDPublicKey.prototype.derive = function derive(index, hardened) {
   if (this.depth >= 0xff)
     throw new Error('Depth too high.');
 
-  id = this.getID(index);
-  child = HD.cache.get(id);
-
-  if (child)
-    return child;
+  if (cache) {
+    id = this.getID(index);
+    child = cache.get(id);
+    if (child)
+      return child;
+  }
 
   p = new BufferWriter();
   p.writeBytes(this.publicKey);
@@ -187,7 +197,8 @@ HDPublicKey.prototype.derive = function derive(index, hardened) {
   child.chainCode = right;
   child.publicKey = key;
 
-  HD.cache.set(id, child);
+  if (cache)
+    cache.set(id, child);
 
   return child;
 };
@@ -288,13 +299,13 @@ HDPublicKey.isValidPath = function isValidPath(path) {
  * @throws Error if hardened.
  */
 
-HDPublicKey.prototype.derivePath = function derivePath(path) {
+HDPublicKey.prototype.derivePath = function derivePath(path, cache) {
   var indexes = HD.parsePath(path, constants.hd.HARDENED);
   var key = this;
   var i;
 
   for (i = 0; i < indexes.length; i++)
-    key = key.derive(indexes[i]);
+    key = key.derive(indexes[i], cache);
 
   return key;
 };