diff --git a/lib/bcoin/tx.js b/lib/bcoin/tx.js
index 923371ec..e89a1509 100644
--- a/lib/bcoin/tx.js
+++ b/lib/bcoin/tx.js
@@ -69,11 +69,8 @@ function TX(data, block) {
   this.ps = this.ts === 0 ? utils.now() : 0;
 
   // Discourage fee snipping a la bitcoind
-  // if (data.lock == null && this.chain) {
-  //   this.lock = this.chain.height();
-  //   if ((Math.random() * 10 | 0) === 0)
-  //     this.lock = Math.max(0, this.lock - (Math.random() * 100 | 0));
-  // }
+  // if (data.lock == null)
+  //   this._avoidFeeSnipping();
 }
 
 TX.prototype.clone = function clone() {
@@ -136,14 +133,6 @@ TX.prototype._input = function _input(obj, index) {
     seq: options.seq
   });
 
-  // Locktime won't work without a seq < uint32max
-  // if (this.lock !== 0)
-  //   input.seq = 0;
-
-  // Replace by fee opt-in
-  // if (this.rbf)
-  //   input.seq = 0xffffffff - 1;
-
   // Try modifying existing input first
   i = this._inputIndex(input.out.hash, input.out.index);
   if (i !== -1) {
@@ -958,6 +947,9 @@ TX.prototype.getUnspent = function getUnspent(unspent, address, fee) {
 TX.prototype.fillUnspent = function fillUnspent(unspent, address, fee) {
   var result;
 
+  if (unspent)
+    this.unspent = unspent;
+
   if (address)
     this.changeAddress = address;
 
@@ -966,7 +958,7 @@ TX.prototype.fillUnspent = function fillUnspent(unspent, address, fee) {
 
   assert(this.changeAddress);
 
-  result = this.getUnspent(unspent, this.changeAddress, this.hardFee);
+  result = this.getUnspent(this.unspent, this.changeAddress, this.hardFee);
 
   if (!result.inputs)
     return result;
@@ -1013,6 +1005,9 @@ TX.prototype._recalculateFee = function recalculateFee() {
   real = Math.ceil(size / 1024) * constants.tx.fee;
   fee = this.getFee().toNumber();
 
+  // if (this.hardFee)
+  //   real = this.hardFee;
+
   if (real === fee) {
     if (this.changeIndex === -1)
       this.outputs.pop();
@@ -1076,6 +1071,40 @@ TX.prototype.funds = function funds(side) {
   return acc;
 };
 
+TX.prototype._avoidFeeSnipping = function _avoidFeeSnipping() {
+  if (!this.chain)
+    return;
+
+  this.lock = this.chain.height();
+
+  if ((Math.random() * 10 | 0) === 0)
+    this.lock = Math.max(0, this.lock - (Math.random() * 100 | 0));
+};
+
+TX.prototype.setLockTime = function setLockTime(lock) {
+  var i, input;
+
+  this.lock = lock;
+
+  for (i = 0; i < this.inputs.length; i++) {
+    input = this.inputs[i];
+    if (input.seq === 0xffffffff)
+      input.seq = 0;
+  }
+};
+
+TX.prototype.increaseFee = function increaseFee(fee) {
+  var i, input;
+
+  this.hardFee = fee || this.getFee().add(new bn(10000));
+  this.fillUnspent();
+
+  for (i = 0; i < this.inputs.length; i++) {
+    input = this.inputs[i];
+    input.seq = 0xffffffff - 1;
+  }
+};
+
 TX.prototype.full = function full() {
   if (this.inputs.length === 0)
     return false;