diff --git a/splitter/simple/impl.go b/splitter/simple/impl.go
index e79dbcd..c7c82cf 100644
--- a/splitter/simple/impl.go
+++ b/splitter/simple/impl.go
@@ -217,8 +217,12 @@ func (m *SimpleMapper) Submit(event *proxy.SubmitEvent) {
 	}
 	m.mu.Lock()
 	defer m.mu.Unlock()
-	seq := m.strategy.Submit(event.JobID, event.Nonce, event.Result, event.Algo)
-	m.pending[seq] = submitContext{RequestID: event.RequestID, StartedAt: time.Now()}
+	jobID := event.JobID
+	if jobID == "" {
+		jobID = m.currentJob.JobID
+	}
+	seq := m.strategy.Submit(jobID, event.Nonce, event.Result, event.Algo)
+	m.pending[seq] = submitContext{RequestID: event.RequestID, StartedAt: time.Now(), JobID: jobID}
 }
 
 // OnJob forwards the latest pool job to the active miner.
@@ -227,6 +231,7 @@ func (m *SimpleMapper) OnJob(job proxy.Job) {
 		return
 	}
 	m.mu.Lock()
+	m.prevJob = m.currentJob
 	m.currentJob = job
 	miner := m.miner
 	m.mu.Unlock()
@@ -247,6 +252,8 @@ func (m *SimpleMapper) OnResultAccepted(sequence int64, accepted bool, errorMess
 		delete(m.pending, sequence)
 	}
 	miner := m.miner
+	currentJob := m.currentJob
+	prevJob := m.prevJob
 	m.mu.Unlock()
 	if !ok || miner == nil {
 		return
@@ -260,17 +267,21 @@ func (m *SimpleMapper) OnResultAccepted(sequence int64, accepted bool, errorMess
 			latency = uint16(elapsed)
 		}
 	}
+	job := currentJob
+	expired := false
+	if ctx.JobID != "" && ctx.JobID == prevJob.JobID && ctx.JobID != currentJob.JobID {
+		job = prevJob
+		expired = true
+	}
 	if accepted {
 		miner.Success(ctx.RequestID, "OK")
 		if m.events != nil {
-			job := miner.CurrentJob()
-			m.events.Dispatch(proxy.Event{Type: proxy.EventAccept, Miner: miner, Diff: job.DifficultyFromTarget(), Job: &job, Latency: latency})
+			m.events.Dispatch(proxy.Event{Type: proxy.EventAccept, Miner: miner, Diff: job.DifficultyFromTarget(), Job: &job, Latency: latency, Expired: expired})
 		}
 		return
 	}
 	miner.ReplyWithError(ctx.RequestID, errorMessage)
 	if m.events != nil {
-		job := miner.CurrentJob()
 		m.events.Dispatch(proxy.Event{Type: proxy.EventReject, Miner: miner, Diff: job.DifficultyFromTarget(), Job: &job, Error: errorMessage, Latency: latency})
 	}
 }
diff --git a/splitter/simple/impl_test.go b/splitter/simple/impl_test.go
index 0ebfaef..8bcffef 100644
--- a/splitter/simple/impl_test.go
+++ b/splitter/simple/impl_test.go
@@ -1,6 +1,9 @@
 package simple
 
 import (
+	"io"
+	"net"
+	"sync"
 	"testing"
 	"time"
 
@@ -112,3 +115,51 @@ func TestSimpleSplitter_Upstreams_Ugly(t *testing.T) {
 		t.Fatalf("expected total upstreams to be 2, got %d", stats.Total)
 	}
 }
+
+type discardConn struct{}
+
+func (discardConn) Read([]byte) (int, error)         { return 0, io.EOF }
+func (discardConn) Write(p []byte) (int, error)      { return len(p), nil }
+func (discardConn) Close() error                     { return nil }
+func (discardConn) LocalAddr() net.Addr              { return nil }
+func (discardConn) RemoteAddr() net.Addr             { return nil }
+func (discardConn) SetDeadline(time.Time) error      { return nil }
+func (discardConn) SetReadDeadline(time.Time) error  { return nil }
+func (discardConn) SetWriteDeadline(time.Time) error { return nil }
+
+func TestSimpleMapper_OnResultAccepted_Expired(t *testing.T) {
+	bus := proxy.NewEventBus()
+	events := make(chan proxy.Event, 1)
+	var once sync.Once
+	bus.Subscribe(proxy.EventAccept, func(e proxy.Event) {
+		once.Do(func() {
+			events <- e
+		})
+	})
+
+	miner := proxy.NewMiner(discardConn{}, 3333, nil)
+	miner.SetID(1)
+	mapper := &SimpleMapper{
+		miner:      miner,
+		currentJob: proxy.Job{JobID: "job-new", Blob: "blob-new", Target: "b88d0600"},
+		prevJob:    proxy.Job{JobID: "job-old", Blob: "blob-old", Target: "b88d0600"},
+		events:     bus,
+		pending: map[int64]submitContext{
+			7: {RequestID: 9, StartedAt: time.Now(), JobID: "job-old"},
+		},
+	}
+
+	mapper.OnResultAccepted(7, true, "")
+
+	select {
+	case event := <-events:
+		if !event.Expired {
+			t.Fatalf("expected expired share to be flagged")
+		}
+		if event.Job == nil || event.Job.JobID != "job-old" {
+			t.Fatalf("expected previous job to be attached, got %+v", event.Job)
+		}
+	case <-time.After(time.Second):
+		t.Fatal("expected accept event")
+	}
+}
diff --git a/splitter/simple/mapper.go b/splitter/simple/mapper.go
index c3b3e40..a37ebca 100644
--- a/splitter/simple/mapper.go
+++ b/splitter/simple/mapper.go
@@ -17,6 +17,7 @@ type SimpleMapper struct {
 	id         int64
 	miner      *proxy.Miner // nil when idle
 	currentJob proxy.Job
+	prevJob    proxy.Job
 	strategy   pool.Strategy
 	idleAt     time.Time // zero when active
 	stopped    bool
@@ -28,4 +29,5 @@ type SimpleMapper struct {
 type submitContext struct {
 	RequestID int64
 	StartedAt time.Time
+	JobID     string
 }