diff --git a/lib/bcoin/chain.js b/lib/bcoin/chain.js
index 5c520f5c..d4ac891c 100644
--- a/lib/bcoin/chain.js
+++ b/lib/bcoin/chain.js
@@ -187,11 +187,14 @@ Chain.prototype.__defineGetter__('height', function() {
 
 Chain.prototype._lock = function _lock(func, args, force) {
   var self = this;
-  var block;
+  var block, called;
 
   if (force) {
     assert(this.busy);
-    return function() {};
+    return function unlock() {
+      assert(!called);
+      called = true;
+    };
   }
 
   if (this.busy) {
@@ -214,6 +217,9 @@ Chain.prototype._lock = function _lock(func, args, force) {
   return function unlock() {
     var item, block;
 
+    assert(!called);
+    called = true;
+
     self.busy = false;
 
     if (func === Chain.prototype.add) {
@@ -584,9 +590,6 @@ Chain.prototype._checkDuplicates = function _checkDuplicates(block, prev, callba
 
     // BIP30 - Ensure there are no duplicate txids
     self.blockdb.hasTX(hash, function(err, result) {
-      if (called)
-        return;
-
       if (err)
         return done(err);
 
@@ -759,8 +762,6 @@ Chain.prototype.resetHeight = function resetHeight(height, force) {
   // no longer need.
   this.purgeOrphans();
   this.purgePending();
-
-  unlock();
 };
 
 Chain.prototype.resetHeightAsync = function resetHeightAsync(height, callback, force) {
@@ -1262,6 +1263,9 @@ Chain.prototype.add = function add(initial, peer, callback, force) {
     if (self.orphan.size > self.orphanLimit)
       self.pruneOrphans();
 
+    // Keep track of total blocks handled.
+    self.total += total;
+
     // We intentionally did not asyncify the
     // callback so if it calls chain.add, it
     // still gets added to the queue. The
@@ -1269,15 +1273,11 @@ Chain.prototype.add = function add(initial, peer, callback, force) {
     // so we don't cause a stack overflow if
     // these end up being all sync chain.adds.
     utils.nextTick(function() {
-      // XXX Possibly put `unlock()` above callback!
+      unlock();
       if (err)
         callback(err);
       else
         callback(null, total);
-
-      self.total += total;
-
-      unlock();
     });
   }
 };
diff --git a/lib/bcoin/chaindb.js b/lib/bcoin/chaindb.js
index 8331ce03..1d573ce6 100644
--- a/lib/bcoin/chaindb.js
+++ b/lib/bcoin/chaindb.js
@@ -123,8 +123,7 @@ ChainDB.prototype.load = function load(start, callback) {
       utils.debug(
         'Blockchain is corrupt after height %d. Resetting.',
         height);
-      self.resetHeightAsync(height, callback);
-      return;
+      return self.resetHeightAsync(height, callback);
     }
     utils.debug('Chain successfully loaded.');
     callback();
@@ -157,6 +156,7 @@ ChainDB.prototype.closeSync = function closeSync() {
     this.ramdisk = null;
     return;
   }
+
   fs.close(this.fd);
   this.fd = null;
 };
@@ -174,6 +174,7 @@ ChainDB.prototype.closeAsync = function closeAsync(callback) {
   fs.close(this.fd, function(err) {
     if (err)
       return callback(err);
+
     self.fd = null;
     return callback();
   });
@@ -349,7 +350,7 @@ ChainDB.prototype.saveSync = function saveSync(entry) {
 
   if (entry.height * BLOCK_SIZE !== this.size) {
     utils.debug('Warning attempt to write to height: %d/%d', this.height);
-    return;
+    return false;
   }
 
   // Cache the past 1001 blocks in memory
@@ -402,8 +403,10 @@ ChainDB.prototype.saveAsync = function saveAsync(entry, callback) {
       return callback(err);
 
     assert(self.queue[entry.height]);
+
     delete self.queue[entry.height];
     self.queueSize--;
+
     if (self.queueSize === 0)
       self.emit('flush');
 
@@ -411,44 +414,39 @@ ChainDB.prototype.saveAsync = function saveAsync(entry, callback) {
   });
 };
 
-ChainDB.prototype._drop = function _drop(height) {
-  assert(height >= 0);
-
-  // Potential race condition here. Not sure how
-  // to handle this.
-  if (this.queue[height]) {
-    utils.debug('Warning: write job in progress.');
-    // delete this.queue[height];
-  }
-
-  delete this.cache[height];
-};
-
 ChainDB.prototype.resetHeightSync = function resetHeightSync(height) {
   var self = this;
-  var size, count, existing;
   var osize = this.size;
   var ohighest = this.highest;
   var otip = this.tip;
+  var size, count, existing;
 
   if (typeof height === 'string')
     height = this.heightLookup[height];
 
   assert(height >= 0);
+  assert(this.tip);
 
   size = (height + 1) * BLOCK_SIZE;
   count = this.getSize();
 
+  if (height > count - 1)
+    throw new Error('Height too high.');
+
   if (height === count - 1)
     return;
 
-  assert(height <= count - 1);
-  assert(this.tip);
-
   for (i = height + 1; i < count; i++) {
     existing = this.getSync(i);
+
     assert(existing);
-    this._drop(i);
+
+    // Warn of potential race condition
+    // (handled with _onFlush).
+    if (this.queue[i])
+      utils.debug('Warning: write job in progress.');
+
+    delete this.cache[i];
     delete this.heightLookup[existing.hash];
   }
 
@@ -481,28 +479,29 @@ ChainDB.prototype.resetHeightSync = function resetHeightSync(height) {
 
 ChainDB.prototype.resetHeightAsync = function resetHeightAsync(height, callback) {
   var self = this;
-  var size, count, pending, called;
   var osize = this.size;
   var ohighest = this.highest;
   var otip = this.tip;
+  var size, count, pending, called;
+
+  callback = utils.asyncify(callback);
 
   if (typeof height === 'string')
     height = this.heightLookup[height];
 
   assert(height >= 0);
-
-  callback = utils.asyncify(callback);
+  assert(this.tip);
 
   size = (height + 1) * BLOCK_SIZE;
   count = this.getSize();
   pending = count - (height + 1);
 
+  if (height > count - 1)
+    return callback(new Error('Height too high'));
+
   if (height === count - 1)
     return callback();
 
-  assert(height <= count - 1);
-  assert(this.tip);
-
   // Prevent any more writes
   // by setting this early.
   this.size = size;
@@ -527,8 +526,14 @@ ChainDB.prototype.resetHeightAsync = function resetHeightAsync(height, callback)
 
         assert(existing);
 
-        self._drop(i);
+        // Warn of potential race condition
+        // (handled with _onFlush).
+        if (self.queue[i])
+          utils.debug('Warning: write job in progress.');
+
+        delete self.cache[i];
         delete self.heightLookup[existing.hash];
+
         if (!--pending)
           done();
       }, true);
diff --git a/lib/bcoin/mempool.js b/lib/bcoin/mempool.js
index 9dd2ebfa..c873128f 100644
--- a/lib/bcoin/mempool.js
+++ b/lib/bcoin/mempool.js
@@ -19,7 +19,7 @@ var fs = bcoin.fs;
  * Mempool
  */
 
-function Mempool(pool, options) {
+function Mempool(node, options) {
   if (!(this instanceof Mempool))
     return new Mempool(pool, options);
 
@@ -27,8 +27,8 @@ function Mempool(pool, options) {
     options = {};
 
   this.options = options;
-  this.pool = pool;
-  this.blockdb = pool.blockdb;
+  this.node = node;
+  this.blockdb = node.blockdb;
 
   this.txs = {};
   this.spent = {};
@@ -235,7 +235,7 @@ Mempool.prototype.addTX = function addTX(tx, peer, callback) {
         data: tx.hash(),
         reason: 'non-standard'
       });
-      pool.setMisbehavior(peer, 100);
+      self.node.pool.setMisbehavior(peer, 100);
       return callback(new Error('TX is not standard.'));
     }
 
@@ -245,7 +245,7 @@ Mempool.prototype.addTX = function addTX(tx, peer, callback) {
         data: tx.hash(),
         reason: 'non-standard-inputs'
       });
-      pool.setMisbehavior(peer, 100);
+      self.node.pool.setMisbehavior(peer, 100);
       return callback(new Error('TX inputs are not standard.'));
     }
 
@@ -255,11 +255,11 @@ Mempool.prototype.addTX = function addTX(tx, peer, callback) {
         data: tx.hash(),
         reason: 'nonexistent-coins'
       });
-      pool.setMisbehavior(peer, 100);
+      self.node.pool.setMisbehavior(peer, 100);
       return callback(new Error('TX is spending coins that it does not have.'));
     }
 
-    height = self.pool.chain.height + 1;
+    height = self.node.pool.chain.height + 1;
     ts = utils.now();
     if (!tx.isFinal(height, ts)) {
       return callback(new Error('TX is not final.'));
@@ -267,7 +267,7 @@ Mempool.prototype.addTX = function addTX(tx, peer, callback) {
         data: tx.hash(),
         reason: 'not-final'
       });
-      pool.setMisbehavior(peer, 100);
+      self.node.pool.setMisbehavior(peer, 100);
       return callback(new Error('TX is not final.'));
     }
 
@@ -299,7 +299,7 @@ Mempool.prototype.addTX = function addTX(tx, peer, callback) {
           data: tx.hash(),
           reason: 'negative-value'
         });
-        pool.setMisbehavior(peer, 100);
+        self.node.pool.setMisbehavior(peer, 100);
         return callback(new Error('TX is spending negative coins.'));
       }
     }
@@ -310,7 +310,7 @@ Mempool.prototype.addTX = function addTX(tx, peer, callback) {
         data: tx.hash(),
         reason: 'script-failed'
       });
-      pool.setMisbehavior(peer, 100);
+      self.node.pool.setMisbehavior(peer, 100);
       return callback(new Error('TX did not verify.'));
     }
 
diff --git a/lib/bcoin/miner.js b/lib/bcoin/miner.js
index d9b190d5..905fb1a3 100644
--- a/lib/bcoin/miner.js
+++ b/lib/bcoin/miner.js
@@ -17,7 +17,7 @@ var EventEmitter = require('events').EventEmitter;
  * Miner
  */
 
-function Miner(options) {
+function Miner(pool, options) {
   if (!(this instanceof Miner))
     return new Miner(options);
 
@@ -30,15 +30,17 @@ function Miner(options) {
   this.address = this.options.address;
   this.msg = this.options.msg || 'mined by bcoin';
 
-  this.pool = options.pool || bcoin.pool.global;
-  this.chain = options.chain || this.pool.chain || bcoin.chain.global;
+  this.pool = pool || bcoin.pool.global;
+  this.chain = this.pool.chain;
+  this.mempool = this.pool.mempool;
+  this.blockdb = this.pool.blockdb;
 
   this.running = false;
   this.timeout = null;
   this.interval = null;
 
   this.fee = new bn(0);
-  this.last = this.chain.getTip();
+  this.last = this.chain.tip;
   this.block = null;
   this.iterations = 0;
   this._begin = utils.now();
@@ -51,18 +53,26 @@ inherits(Miner, EventEmitter);
 Miner.prototype._init = function _init() {
   var self = this;
 
-  this.pool.on('tx', function(tx) {
-    self.addTX(tx);
-  });
+  if (this.mempool) {
+    this.mempool.on('tx', function(tx) {
+      if (!self.running)
+        return;
+      self.addTX(tx);
+    });
+  } else {
+    this.pool.on('tx', function(tx) {
+      if (!self.running)
+        return;
+      self.addTX(tx);
+    });
+  }
 
-  this.chain.on('block', function(block) {
+  this.chain.on('add block', function(block) {
+    if (!self.running)
+      return;
     self.addBlock(block);
   });
 
-  // this.chain.on('tip', function(entry) {
-  //   self.addBlock(entry);
-  // });
-
   this.on('block', function(block) {
     utils.debug(
       'Found block: %d (%s)',
@@ -123,7 +133,10 @@ Miner.prototype.add = function add(msg) {
 
 Miner.prototype.addBlock = function addBlock(block) {
   if (!block)
-    block = this.chain.getTip();
+    block = this.chain.tip;
+
+  if (!this.last)
+    this.last = this.chain.tip;
 
   // Somebody found the next block before
   // us, start over with the new target.
@@ -222,7 +235,7 @@ Miner.prototype.createBlock = function createBlock(tx) {
     seq: 0xffffffff
   });
 
-  if (script.getSize(coinbase.inputs[0].script) > 100)
+  if (bcoin.script.getSize(coinbase.inputs[0].script) > 100)
     throw new Error('Coinbase script is too large');
 
   coinbase.addOutput({
diff --git a/lib/bcoin/node.js b/lib/bcoin/node.js
index 3b7fe3bb..1db5b47c 100644
--- a/lib/bcoin/node.js
+++ b/lib/bcoin/node.js
@@ -39,6 +39,7 @@ function Node(options) {
   this.mempool = null;
   this.pool = null;
   this.chain = null;
+  this.miner = null;
 
   Node.global = this;
 
@@ -50,18 +51,19 @@ inherits(Node, EventEmitter);
 Node.prototype._init = function _init() {
   var self = this;
 
-  this.blockdb = new bcoin.blockdb(this.options.blockdb);
-  this.mempool = new bcoin.mempool(this, this.options.mempool);
-
   if (!this.options.pool)
     this.options.pool = {};
 
+  this.blockdb = new bcoin.blockdb(this.options.blockdb);
+  this.mempool = new bcoin.mempool(this, this.options.mempool);
+
   this.options.pool.spv = false;
   this.options.pool.blockdb = this.blockdb;
   this.options.pool.mempool = this.mempool;
 
   this.pool = new bcoin.pool(this.options.pool);
   this.chain = this.pool.chain;
+  this.miner = new bcoin.miner(this.pool, this.options.miner);
 
   this.mempool.on('error', function(err) {
     self.emit('error', err);