diff --git a/lib/coins/coins.js b/lib/coins/coins.js
index 37c0b547..287ecfe0 100644
--- a/lib/coins/coins.js
+++ b/lib/coins/coins.js
@@ -13,13 +13,12 @@ const CoinEntry = require('./coinentry');
  * Represents the outputs for a single transaction.
  * @alias module:coins.Coins
  * @constructor
- * @property {Hash} hash - Transaction hash.
- * @property {CoinEntry[]} outputs - Coins.
+ * @property {Map[]} outputs - Coins.
  */
 
-function Coins(options) {
+function Coins() {
   if (!(this instanceof Coins))
-    return new Coins(options);
+    return new Coins();
 
   this.outputs = new Map();
 }
@@ -28,35 +27,39 @@ function Coins(options) {
  * Add a single entry to the collection.
  * @param {Number} index
  * @param {CoinEntry} coin
+ * @returns {CoinEntry}
  */
 
 Coins.prototype.add = function add(index, coin) {
   assert(index >= 0);
-
   assert(!this.outputs.has(index));
 
   this.outputs.set(index, coin);
+
+  return coin;
 };
 
 /**
  * Add a single output to the collection.
  * @param {Number} index
  * @param {Output} output
+ * @returns {CoinEntry}
  */
 
 Coins.prototype.addOutput = function addOutput(index, output) {
   assert(!output.script.isUnspendable());
-  this.add(index, CoinEntry.fromOutput(output));
+  return this.add(index, CoinEntry.fromOutput(output));
 };
 
 /**
  * Add a single coin to the collection.
  * @param {Coin} coin
+ * @returns {CoinEntry}
  */
 
 Coins.prototype.addCoin = function addCoin(coin) {
   assert(!coin.script.isUnspendable());
-  this.add(coin.index, CoinEntry.fromCoin(coin));
+  return this.add(coin.index, CoinEntry.fromCoin(coin));
 };
 
 /**
@@ -87,24 +90,24 @@ Coins.prototype.isUnspent = function isUnspent(index) {
 /**
  * Get a coin entry.
  * @param {Number} index
- * @returns {CoinEntry}
+ * @returns {CoinEntry|null}
  */
 
 Coins.prototype.get = function get(index) {
-  return this.outputs.get(index);
+  return this.outputs.get(index) || null;
 };
 
 /**
  * Get an output.
  * @param {Number} index
- * @returns {Output}
+ * @returns {Output|null}
  */
 
 Coins.prototype.getOutput = function getOutput(index) {
   let coin = this.outputs.get(index);
 
   if (!coin)
-    return;
+    return null;
 
   return coin.output;
 };
@@ -112,14 +115,14 @@ Coins.prototype.getOutput = function getOutput(index) {
 /**
  * Get a coin.
  * @param {Outpoint} prevout
- * @returns {Coin}
+ * @returns {Coin|null}
  */
 
 Coins.prototype.getCoin = function getCoin(prevout) {
   let coin = this.outputs.get(prevout.index);
 
   if (!coin)
-    return;
+    return null;
 
   return coin.toCoin(prevout);
 };
@@ -127,14 +130,14 @@ Coins.prototype.getCoin = function getCoin(prevout) {
 /**
  * Spend a coin entry and return it.
  * @param {Number} index
- * @returns {CoinEntry}
+ * @returns {CoinEntry|null}
  */
 
 Coins.prototype.spend = function spend(index) {
   let coin = this.get(index);
 
   if (!coin || coin.spent)
-    return;
+    return null;
 
   coin.spent = true;
 
@@ -144,38 +147,20 @@ Coins.prototype.spend = function spend(index) {
 /**
  * Remove a coin entry and return it.
  * @param {Number} index
- * @returns {CoinEntry}
+ * @returns {CoinEntry|null}
  */
 
 Coins.prototype.remove = function remove(index) {
   let coin = this.get(index);
 
   if (!coin)
-    return false;
+    return null;
 
   this.outputs.delete(index);
 
   return coin;
 };
 
-/**
- * Calculate unspent length of coins.
- * @returns {Number}
- */
-
-Coins.prototype.length = function length() {
-  let len = -1;
-
-  for (let [index, coin] of this.outputs) {
-    if (!coin.spent) {
-      if (index > len)
-        len = index;
-    }
-  }
-
-  return len + 1;
-};
-
 /**
  * Test whether the coins are fully spent.
  * @returns {Boolean}
@@ -190,6 +175,7 @@ Coins.prototype.isEmpty = function isEmpty() {
  * @private
  * @param {TX} tx
  * @param {Number} height
+ * @returns {Coins}
  */
 
 Coins.prototype.fromTX = function fromTX(tx, height) {
diff --git a/lib/coins/coinview.js b/lib/coins/coinview.js
index 029611c7..2b30ac5f 100644
--- a/lib/coins/coinview.js
+++ b/lib/coins/coinview.js
@@ -51,6 +51,7 @@ CoinView.prototype.has = function has(hash) {
  * Add coins to the collection.
  * @param {Hash} hash
  * @param {Coins} coins
+ * @returns {Coins}
  */
 
 CoinView.prototype.add = function add(hash, coins) {
@@ -61,49 +62,55 @@ CoinView.prototype.add = function add(hash, coins) {
 /**
  * Remove coins from the collection.
  * @param {Coins} coins
- * @returns {Boolean}
+ * @returns {Coins|null}
  */
 
 CoinView.prototype.remove = function remove(hash) {
-  if (!this.map.has(hash))
-    return false;
+  let coins = this.map.get(hash);
+
+  if (!coins)
+    return null;
 
   this.map.delete(hash);
 
-  return true;
+  return coins;
 };
 
 /**
  * Add a tx to the collection.
  * @param {TX} tx
  * @param {Number} height
+ * @returns {Coins}
  */
 
 CoinView.prototype.addTX = function addTX(tx, height) {
+  let hash = tx.hash('hex');
   let coins = Coins.fromTX(tx, height);
-  return this.add(tx.hash('hex'), coins);
+  return this.add(hash, coins);
 };
 
 /**
  * Remove a tx from the collection.
  * @param {TX} tx
  * @param {Number} height
+ * @returns {Coins}
  */
 
 CoinView.prototype.removeTX = function removeTX(tx, height) {
+  let hash = tx.hash('hex');
   let coins = Coins.fromTX(tx, height);
 
   for (let coin of coins.outputs.values())
     coin.spent = true;
 
-  return this.add(tx.hash('hex'), coins);
+  return this.add(hash, coins);
 };
 
 /**
  * Add an entry to the collection.
  * @param {Outpoint} prevout
  * @param {CoinEntry} coin
- * @returns {Coins|null}
+ * @returns {CoinEntry|null}
  */
 
 CoinView.prototype.addEntry = function addEntry(prevout, coin) {
@@ -116,17 +123,18 @@ CoinView.prototype.addEntry = function addEntry(prevout, coin) {
   }
 
   if (coin.output.script.isUnspendable())
-    return;
+    return null;
 
-  if (!coins.has(index))
-    coins.add(index, coin);
+  if (coins.has(index))
+    return null;
 
-  return coins;
+  return coins.add(index, coin);
 };
 
 /**
  * Add a coin to the collection.
  * @param {Coin} coin
+ * @returns {CoinEntry|null}
  */
 
 CoinView.prototype.addCoin = function addCoin(coin) {
@@ -139,18 +147,19 @@ CoinView.prototype.addCoin = function addCoin(coin) {
   }
 
   if (coin.script.isUnspendable())
-    return;
+    return null;
 
-  if (!coins.has(index))
-    coins.addCoin(coin);
+  if (coins.has(index))
+    return null;
 
-  return coins;
+  return coins.addCoin(coin);
 };
 
 /**
  * Add an output to the collection.
  * @param {Outpoint} prevout
  * @param {Output} output
+ * @returns {CoinEntry|null}
  */
 
 CoinView.prototype.addOutput = function addOutput(prevout, output) {
@@ -163,16 +172,18 @@ CoinView.prototype.addOutput = function addOutput(prevout, output) {
   }
 
   if (output.script.isUnspendable())
-    return;
+    return null;
 
-  if (!coins.has(index))
-    coins.addOutput(index, output);
+  if (coins.has(index))
+    return null;
+
+  return coins.addOutput(index, output);
 };
 
 /**
  * Spend an output.
  * @param {Outpoint} prevout
- * @returns {Boolean}
+ * @returns {CoinEntry|null}
  */
 
 CoinView.prototype.spendOutput = function spendOutput(prevout) {
@@ -181,22 +192,22 @@ CoinView.prototype.spendOutput = function spendOutput(prevout) {
   let coin;
 
   if (!coins)
-    return false;
+    return null;
 
   coin = coins.spend(index);
 
   if (!coin)
-    return false;
+    return null;
 
   this.undo.push(coin);
 
-  return true;
+  return coin;
 };
 
 /**
  * Remove an output.
  * @param {Outpoint} prevout
- * @returns {Boolean}
+ * @returns {CoinEntry|null}
  */
 
 CoinView.prototype.removeOutput = function removeOutput(prevout) {
@@ -204,7 +215,7 @@ CoinView.prototype.removeOutput = function removeOutput(prevout) {
   let coins = this.get(hash);
 
   if (!coins)
-    return false;
+    return null;
 
   return coins.remove(index);
 };
@@ -226,9 +237,9 @@ CoinView.prototype.hasEntry = function hasEntry(prevout) {
 };
 
 /**
- * Get a single entry by input.
+ * Get a single entry by prevout.
  * @param {Outpoint} prevout
- * @returns {CoinEntry}
+ * @returns {CoinEntry|null}
  */
 
 CoinView.prototype.getEntry = function getEntry(prevout) {
@@ -236,7 +247,7 @@ CoinView.prototype.getEntry = function getEntry(prevout) {
   let coins = this.get(hash);
 
   if (!coins)
-    return;
+    return null;
 
   return coins.get(index);
 };
@@ -244,14 +255,14 @@ CoinView.prototype.getEntry = function getEntry(prevout) {
 /**
  * Get a single coin by prevout.
  * @param {Outpoint} prevout
- * @returns {Coin}
+ * @returns {Coin|null}
  */
 
 CoinView.prototype.getCoin = function getCoin(prevout) {
   let coins = this.get(prevout.hash);
 
   if (!coins)
-    return;
+    return null;
 
   return coins.getCoin(prevout);
 };
@@ -259,7 +270,7 @@ CoinView.prototype.getCoin = function getCoin(prevout) {
 /**
  * Get a single output by prevout.
  * @param {Outpoint} prevout
- * @returns {Output}
+ * @returns {Output|null}
  */
 
 CoinView.prototype.getOutput = function getOutput(prevout) {
@@ -267,7 +278,7 @@ CoinView.prototype.getOutput = function getOutput(prevout) {
   let coins = this.get(hash);
 
   if (!coins)
-    return;
+    return null;
 
   return coins.getOutput(index);
 };
@@ -315,7 +326,7 @@ CoinView.prototype.hasEntryFor = function hasEntryFor(input) {
 /**
  * Get a single entry by input.
  * @param {Input} input
- * @returns {CoinEntry}
+ * @returns {CoinEntry|null}
  */
 
 CoinView.prototype.getEntryFor = function getEntryFor(input) {
@@ -325,7 +336,7 @@ CoinView.prototype.getEntryFor = function getEntryFor(input) {
 /**
  * Get a single coin by input.
  * @param {Input} input
- * @returns {Coin}
+ * @returns {Coin|null}
  */
 
 CoinView.prototype.getCoinFor = function getCoinFor(input) {
@@ -335,7 +346,7 @@ CoinView.prototype.getCoinFor = function getCoinFor(input) {
 /**
  * Get a single output by input.
  * @param {Input} input
- * @returns {Output}
+ * @returns {Output|null}
  */
 
 CoinView.prototype.getOutputFor = function getOutputFor(input) {
@@ -367,7 +378,7 @@ CoinView.prototype.isCoinbaseFor = function isCoinbaseFor(input) {
  * @method
  * @param {ChainDB} db
  * @param {Outpoint} prevout
- * @returns {Promise} - Returns {@link Coins}.
+ * @returns {Promise} - Returns {@link CoinEntry}.
  */
 
 CoinView.prototype.readCoin = async function readCoin(db, prevout) {
@@ -381,9 +392,7 @@ CoinView.prototype.readCoin = async function readCoin(db, prevout) {
   if (!coin)
     return null;
 
-  this.addEntry(prevout, coin);
-
-  return coin;
+  return this.addEntry(prevout, coin);
 };
 
 /**
diff --git a/test/coins-test.js b/test/coins-test.js
index f55d208b..9c7236bb 100644
--- a/test/coins-test.js
+++ b/test/coins-test.js
@@ -66,7 +66,7 @@ describe('Coins', function() {
 
     coins = view.get(hash);
     assert(coins);
-    length = coins.length();
+    length = coins.outputs.size;
 
     view.spendOutput(new Outpoint(hash, 0));
 
@@ -78,7 +78,7 @@ describe('Coins', function() {
     assert(entry.spent);
 
     deepCoinsEqual(entry, reserialize(entry));
-    assert.strictEqual(coins.length(), length);
+    assert.strictEqual(coins.outputs.size, length);
 
     assert.equal(view.undo.items.length, 1);
   });
@@ -102,8 +102,8 @@ describe('Coins', function() {
     prev = tx1.inputs[0].prevout;
     coins = res.get(prev.hash);
 
-    assert.strictEqual(coins.length(), 2);
-    assert.strictEqual(coins.get(0), undefined);
+    assert.strictEqual(coins.outputs.size, 1);
+    assert.strictEqual(coins.get(0), null);
     deepCoinsEqual(coins.get(1), reserialize(coins.get(1)));
   });
 });