diff --git a/lib/bcoin/miner.js b/lib/bcoin/miner.js
index e62a9bce..d877147c 100644
--- a/lib/bcoin/miner.js
+++ b/lib/bcoin/miner.js
@@ -178,6 +178,8 @@ Miner.prototype.start = function start(version) {
 
     attempt.mineAsync(function(err, block) {
       if (err) {
+        if (!self.running)
+          return;
         self.emit('error', err);
         return self.start();
       }
@@ -363,6 +365,8 @@ function MinerBlock(options) {
   this.witness = options.witness;
   this.address = options.address;
   this.network = bcoin.network.get(options.network);
+  this.timeout = null;
+  this.callback = null;
 
   this.coinbase = new bcoin.tx();
   this.coinbase.mutable = true;
@@ -673,6 +677,10 @@ MinerBlock.prototype.mineAsync = function mine(callback) {
   if (!this.workerPool)
     return this.mine(callback);
 
+  callback = utils.once(callback);
+
+  this.callback = callback;
+
   function done(err, block) {
     self.workerPool.destroy();
     callback(err, block);
@@ -697,6 +705,10 @@ MinerBlock.prototype.destroy = function destroy() {
     clearTimeout(this.timeout);
     this.timeout = null;
   }
+  if (this.callback) {
+    this.callback(new Error('Destroyed.'));
+    this.callback = null;
+  }
   this.block = null;
 };