diff --git a/lib/wallet/wallet.js b/lib/wallet/wallet.js
index e43f97cf..66d746ef 100644
--- a/lib/wallet/wallet.js
+++ b/lib/wallet/wallet.js
@@ -482,7 +482,7 @@ Wallet.prototype.retoken = co(function* retoken(passphrase) {
  */
 
 Wallet.prototype._retoken = co(function* retoken(passphrase) {
-  var master = yield this.unlock(passphrase);
+  yield this.unlock(passphrase);
 
   this.tokenDepth++;
   this.token = this.getToken(this.tokenDepth);
@@ -1483,6 +1483,99 @@ Wallet.prototype._send = co(function* send(options, passphrase) {
   return tx;
 });
 
+/**
+ * Intentionally double-spend outputs by
+ * increasing fee for an existing transaction.
+ * @param {Hash} hash
+ * @param {Rate} rate
+ * @param {(String|Buffer)?} passphrase
+ * @returns {Promise} - Returns {@link TX}.
+ */
+
+Wallet.prototype.increaseFee = co(function* increaseFee(hash, rate, passphrase) {
+  var tx = yield this.getTX(hash);
+  var i, oldFee, fee, path, input, output, change;
+
+  if (!tx)
+    throw new Error('Transaction not found.');
+
+  if (tx.isCoinbase())
+    throw new Error('Transaction is a coinbase.');
+
+  yield this.fillHistory(tx);
+
+  if (!tx.hasCoins())
+    throw new Error('Not all coins available.');
+
+  if (!utils.isUInt32(rate))
+    throw new Error('Rate must be a number.');
+
+  oldFee = tx.getFee();
+  fee = tx.getMinFee(null, rate);
+
+  if (fee > constants.tx.MAX_FEE)
+    fee = constants.tx.MAX_FEE;
+
+  if (oldFee >= fee)
+    throw new Error('Fee is not increasing.');
+
+  tx = MTX.fromRaw(tx.toRaw());
+
+  for (i = 0; i < tx.inputs.length; i++) {
+    input = tx.inputs[i];
+    input.script.length = 0;
+    input.script.compile();
+    input.witness.length = 0;
+    input.witness.compile();
+  }
+
+  for (i = 0; i < tx.outputs.length; i++) {
+    output = tx.outputs[i];
+    path = yield this.getPath(output.getAddress());
+
+    if (!path)
+      continue;
+
+    if (path.branch === 1) {
+      change = output;
+      tx.changeIndex = i;
+      break;
+    }
+  }
+
+  if (!change)
+    throw new Error('No change output.');
+
+  change.value += oldFee;
+
+  if (tx.getFee() !== 0)
+    throw new Error('Arithmetic error for change.');
+
+  change.value -= fee;
+
+  if (change.value < 0)
+    throw new Error('Fee is too high.');
+
+  if (change.isDust(constants.tx.MIN_RELAY)) {
+    tx.outputs.splice(tx.changeIndex, 1);
+    tx.changeIndex = -1;
+  }
+
+  yield this.sign(tx, passphrase);
+
+  if (!tx.isSigned())
+    throw new Error('TX could not be fully signed.');
+
+  tx = tx.toTX();
+
+  this.logger.debug('Increasing fee for wallet tx (%s): %s', this.id, tx.rhash);
+
+  yield this.db.addTX(tx);
+  yield this.db.send(tx);
+
+  return tx;
+});
+
 /**
  * Resend pending wallet transactions.
  * @returns {Promise}
diff --git a/lib/wallet/walletdb.js b/lib/wallet/walletdb.js
index 9f81527b..9f9dee5a 100644
--- a/lib/wallet/walletdb.js
+++ b/lib/wallet/walletdb.js
@@ -1724,7 +1724,7 @@ WalletDB.prototype.rollback = co(function* rollback(height) {
  */
 
 WalletDB.prototype.revert = co(function* revert(height) {
-  var i, iter, item, height, block, tx;
+  var i, iter, item, block, tx;
 
   iter = this.db.iterator({
     gte: layout.b(height + 1),
@@ -1739,7 +1739,6 @@ WalletDB.prototype.revert = co(function* revert(height) {
       break;
 
     try {
-      height = layout.bb(item.key);
       block = BlockMapRecord.fromRaw(item.value);
 
       for (i = block.txs.length - 1; i >= 0; i--) {