diff --git a/lib/blockchain/chain.js b/lib/blockchain/chain.js
index c1f9ef5d..0118a5f4 100644
--- a/lib/blockchain/chain.js
+++ b/lib/blockchain/chain.js
@@ -1161,7 +1161,7 @@ Chain.prototype.onDrain = function onDrain() {
  */
 
 Chain.prototype.isBusy = function isBusy() {
-  return this.locker.busy;
+  return this.locker.isBusy();
 };
 
 /**
diff --git a/lib/net/pool.js b/lib/net/pool.js
index 97e02009..40dc44ed 100644
--- a/lib/net/pool.js
+++ b/lib/net/pool.js
@@ -1071,7 +1071,7 @@ Pool.prototype.handleBlock = co(function* handleBlock(block, peer) {
       + ' ts=%s height=%d highest=%d progress=%s'
       + ' blocks=%d orphans=%d active=%d'
       + ' queue=%d target=%s peers=%d'
-      + ' jobs=%d',
+      + ' pending=%d jobs=%d',
       util.date(block.ts),
       this.chain.height,
       this.chain.bestHeight,
@@ -1082,6 +1082,7 @@ Pool.prototype.handleBlock = co(function* handleBlock(block, peer) {
       peer.queueBlock.size,
       block.bits,
       this.peers.size(),
+      this.chain.locker.pending,
       this.chain.locker.jobs.length);
   }
 
diff --git a/lib/utils/locker.js b/lib/utils/locker.js
index 72e92c46..c761ee28 100644
--- a/lib/utils/locker.js
+++ b/lib/utils/locker.js
@@ -29,6 +29,7 @@ function Locker(named) {
   this.destroyed = false;
 
   this.map = {};
+  this.pending = 0;
   this.current = null;
 
   this.unlocker = this.unlock.bind(this);
@@ -75,6 +76,19 @@ Locker.prototype.hasPending = function hasPending(name) {
   return this.map[name] > 0;
 };
 
+/**
+ * Test whether the locker is
+ * busy with a named job.
+ * @returns {Boolean}
+ */
+
+Locker.prototype.isBusy = function isBusy() {
+  assert(this.named, 'Must use named jobs.');
+  if (this.current)
+    return true;
+  return this.pending > 0;
+};
+
 /**
  * Lock the parent object and all its methods
  * which use the locker. Begin to queue calls.
@@ -110,6 +124,7 @@ Locker.prototype.lock = function lock(arg1, arg2) {
       if (!this.map[name])
         this.map[name] = 0;
       this.map[name]++;
+      this.pending++;
     }
     return new Promise(function(resolve, reject) {
       self.jobs.push(new Job(resolve, reject, name));
@@ -136,6 +151,7 @@ Locker.prototype.unlock = function unlock() {
   this.current = null;
 
   if (this.jobs.length === 0) {
+    assert(this.pending === 0);
     this.drain();
     return;
   }
@@ -148,6 +164,10 @@ Locker.prototype.unlock = function unlock() {
     assert(this.map[job.name] > 0);
     if (--this.map[job.name] === 0)
       delete this.map[job.name];
+    this.pending--;
+  } else {
+    if (this.pending === 0)
+      this.drain();
   }
 
   this.busy = true;
@@ -164,10 +184,12 @@ Locker.prototype.unlock = function unlock() {
 Locker.prototype.wait = function wait() {
   var self = this;
 
+  assert(this.named, 'Must use named jobs.');
+
   if (this.destroyed)
     return Promise.reject(new Error('Locker is destroyed.'));
 
-  if (!this.busy) {
+  if (!this.isBusy()) {
     assert(this.waiting.length === 0);
     return Promise.resolve();
   }
@@ -206,11 +228,17 @@ Locker.prototype.destroy = function destroy() {
   var err = new Error('Locker was destroyed.');
   var i, jobs, job;
 
+  assert(!this.destroyed, 'Locker is already destroyed.');
+
   this.destroyed = true;
 
   jobs = this.jobs.slice();
 
+  this.busy = false;
   this.jobs.length = 0;
+  this.map = {};
+  this.pending = 0;
+  this.current = null;
 
   for (i = 0; i < jobs.length; i++) {
     job = jobs[i];
@@ -265,6 +293,15 @@ MappedLock.prototype.has = function has(name) {
   return this.busy[name] === true;
 };
 
+/**
+ * Test whether the locker is busy .
+ * @returns {Boolean}
+ */
+
+MappedLock.prototype.isBusy = function isBusy() {
+  return this.busy;
+};
+
 /**
  * Lock the parent object and all its methods
  * which use the locker with a specified key.
@@ -346,9 +383,12 @@ MappedLock.prototype.destroy = function destroy() {
   var keys = Object.keys(map);
   var i, j, key, jobs, job;
 
+  assert(!this.destroyed, 'Locker is already destroyed.');
+
   this.destroyed = true;
 
   this.jobs = {};
+  this.busy = {};
 
   for (i = 0; i < keys.length; i++) {
     key = keys[i];