diff --git a/miner/agent.go b/miner/agent.go
index 5661d2982..c650fa2f3 100644
--- a/miner/agent.go
+++ b/miner/agent.go
@@ -1,12 +1,15 @@
 package miner
 
 import (
+	"sync"
+
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/pow"
 )
 
 type CpuMiner struct {
+	chMu          sync.Mutex
 	c             chan *types.Block
 	quit          chan struct{}
 	quitCurrentOp chan struct{}
@@ -43,16 +46,13 @@ func (self *CpuMiner) Start() {
 }
 
 func (self *CpuMiner) update() {
-	justStarted := true
 out:
 	for {
 		select {
 		case block := <-self.c:
-			if justStarted {
-				justStarted = true
-			} else {
-				self.quitCurrentOp <- struct{}{}
-			}
+			self.chMu.Lock()
+			self.quitCurrentOp <- struct{}{}
+			self.chMu.Unlock()
 
 			go self.mine(block)
 		case <-self.quit:
@@ -60,6 +60,7 @@ out:
 		}
 	}
 
+	close(self.quitCurrentOp)
 done:
 	// Empty channel
 	for {
@@ -75,12 +76,20 @@ done:
 
 func (self *CpuMiner) mine(block *types.Block) {
 	minerlogger.Debugf("(re)started agent[%d]. mining...\n", self.index)
+
+	// Reset the channel
+	self.chMu.Lock()
+	self.quitCurrentOp = make(chan struct{}, 1)
+	self.chMu.Unlock()
+
+	// Mine
 	nonce, mixDigest, _ := self.pow.Search(block, self.quitCurrentOp)
 	if nonce != 0 {
 		block.SetNonce(nonce)
 		block.Header().MixDigest = common.BytesToHash(mixDigest)
 		self.returnCh <- block
-		//self.returnCh <- Work{block.Number().Uint64(), nonce, mixDigest, seedHash}
+	} else {
+		self.returnCh <- nil
 	}
 }
 
diff --git a/miner/remote_agent.go b/miner/remote_agent.go
index e92dd5963..aa04a58aa 100644
--- a/miner/remote_agent.go
+++ b/miner/remote_agent.go
@@ -50,6 +50,7 @@ out:
 			break out
 		case work := <-a.workCh:
 			a.work = work
+			a.returnCh <- nil
 		}
 	}
 }
diff --git a/miner/worker.go b/miner/worker.go
index e0287ea8d..e3680dea3 100644
--- a/miner/worker.go
+++ b/miner/worker.go
@@ -5,6 +5,7 @@ import (
 	"math/big"
 	"sort"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -58,13 +59,14 @@ type Agent interface {
 }
 
 type worker struct {
-	mu     sync.Mutex
+	mu sync.Mutex
+
 	agents []Agent
 	recv   chan *types.Block
 	mux    *event.TypeMux
 	quit   chan struct{}
 	pow    pow.PoW
-	atWork int
+	atWork int64
 
 	eth      core.Backend
 	chain    *core.ChainManager
@@ -107,7 +109,7 @@ func (self *worker) start() {
 
 func (self *worker) stop() {
 	self.mining = false
-	self.atWork = 0
+	atomic.StoreInt64(&self.atWork, 0)
 
 	close(self.quit)
 }
@@ -135,9 +137,6 @@ out:
 				self.uncleMu.Unlock()
 			}
 
-			if self.atWork == 0 {
-				self.commitNewWork()
-			}
 		case <-self.quit:
 			// stop all agents
 			for _, agent := range self.agents {
@@ -146,6 +145,11 @@ out:
 			break out
 		case <-timer.C:
 			minerlogger.Infoln("Hash rate:", self.HashRate(), "Khash")
+
+			// XXX In case all mined a possible uncle
+			if atomic.LoadInt64(&self.atWork) == 0 {
+				self.commitNewWork()
+			}
 		}
 	}
 
@@ -155,6 +159,12 @@ out:
 func (self *worker) wait() {
 	for {
 		for block := range self.recv {
+			atomic.AddInt64(&self.atWork, -1)
+
+			if block == nil {
+				continue
+			}
+
 			if err := self.chain.InsertChain(types.Blocks{block}); err == nil {
 				for _, uncle := range block.Uncles() {
 					delete(self.possibleUncles, uncle.Hash())
@@ -170,7 +180,6 @@ func (self *worker) wait() {
 			} else {
 				self.commitNewWork()
 			}
-			self.atWork--
 		}
 	}
 }
@@ -182,8 +191,9 @@ func (self *worker) push() {
 
 		// push new work to agents
 		for _, agent := range self.agents {
+			atomic.AddInt64(&self.atWork, 1)
+
 			agent.Work() <- self.current.block.Copy()
-			self.atWork++
 		}
 	}
 }