diff --git a/lib/bcoin/mtx.js b/lib/bcoin/mtx.js
index bfe7c0b3..f97c8948 100644
--- a/lib/bcoin/mtx.js
+++ b/lib/bcoin/mtx.js
@@ -685,7 +685,10 @@ MTX.prototype.maxSize = function maxSize(maxM, maxN) {
     size = 0;
     witness = false;
 
-    assert(input.coin);
+    if (!input.coin) {
+      total += 110;
+      continue;
+    }
 
     // Get the previous output's subscript
     prev = input.coin.script;
diff --git a/lib/bcoin/protocol/constants.js b/lib/bcoin/protocol/constants.js
index 45f6d271..e891d5b7 100644
--- a/lib/bcoin/protocol/constants.js
+++ b/lib/bcoin/protocol/constants.js
@@ -207,7 +207,6 @@ exports.tx = {
   minFee: 10000,
   bareMultisig: true,
   freeThreshold: exports.coin.muln(144).divn(250),
-  maxFreeSize: 1000,
   maxSigops: exports.block.maxSigops / 5,
   coinbaseMaturity: 100
 };
diff --git a/lib/bcoin/tx.js b/lib/bcoin/tx.js
index 10451d1c..696d6da6 100644
--- a/lib/bcoin/tx.js
+++ b/lib/bcoin/tx.js
@@ -988,27 +988,51 @@ TX.prototype.maxSize = function maxSize() {
   return this.getVirtualSize();
 };
 
+TX.prototype.getModifiedSize = function getModifiedSize(size) {
+  var i, offset;
+
+  if (size == null)
+    size = this.maxSize();
+
+  for (i = 0; i < this.inputs.length; i++) {
+    offset = 41 + Math.min(110, this.inputs[i].script.getSize());
+    if (size > offset)
+      size -= offset;
+  }
+
+  return size;
+};
+
 TX.prototype.getPriority = function getPriority(height, size) {
   var sum, i, input, age;
 
+  if (this.isCoinbase())
+    return new bn(0);
+
   if (height == null) {
     height = this.height;
     if (height === -1)
       height = network.height + 1;
   }
 
-  if (!this.hasCoins())
-    return new bn(0);
-
   if (size == null)
-    size = this.maxSize();
+    size = this.getModifiedSize();
 
   sum = new bn(0);
 
   for (i = 0; i < this.inputs.length; i++) {
     input = this.inputs[i];
-    age = input.coin.getAge(height);
-    sum.iadd(input.coin.value.muln(age));
+
+    if (!input.coin)
+      continue;
+
+    if (input.coin.height === -1)
+      continue;
+
+    if (input.coin.height <= height) {
+      age = height - input.coin.height;
+      sum.iadd(input.coin.value.muln(age));
+    }
   }
 
   return sum.divn(size);
@@ -1017,21 +1041,12 @@ TX.prototype.getPriority = function getPriority(height, size) {
 TX.prototype.isFree = function isFree(height, size) {
   var priority;
 
-  if (!this.hasCoins())
-    return false;
-
   if (height == null) {
     height = this.height;
     if (height === -1)
       height = network.height + 1;
   }
 
-  if (size == null)
-    size = this.maxSize();
-
-  if (size >= constants.tx.maxFreeSize)
-    return false;
-
   priority = this.getPriority(height, size);
 
   return priority.cmp(constants.tx.freeThreshold) > 0;