diff --git a/dispatch/dispatch.go b/dispatch/dispatch.go
index 89080994..ee911152 100644
--- a/dispatch/dispatch.go
+++ b/dispatch/dispatch.go
@@ -329,8 +329,14 @@ func (ag *aggrGroup) flush(notify func(...*types.Alert) bool) {
 		alerts      = ag.alerts.List()
 		alertsSlice = make(types.AlertSlice, 0, ag.alerts.Count())
 	)
+	now := time.Now()
 	for alert := range alerts {
-		alertsSlice = append(alertsSlice, alert)
+		a := *alert
+		// Ensure that alerts don't resolve as time move forwards.
+		if !a.ResolvedAt(now) {
+			a.EndsAt = time.Time{}
+		}
+		alertsSlice = append(alertsSlice, &a)
 	}
 	sort.Stable(alertsSlice)
 
@@ -348,7 +354,7 @@ func (ag *aggrGroup) flush(notify func(...*types.Alert) bool) {
 				level.Error(ag.logger).Log("msg", "failed to get alert", "err", err)
 				continue
 			}
-			if a.Resolved() && got == a {
+			if a.Resolved() && got.UpdatedAt == a.UpdatedAt {
 				if err := ag.alerts.Delete(fp); err != nil {
 					level.Error(ag.logger).Log("msg", "error on delete alert", "err", err)
 				}
diff --git a/dispatch/dispatch_test.go b/dispatch/dispatch_test.go
index 4ec2ab84..8ce94679 100644
--- a/dispatch/dispatch_test.go
+++ b/dispatch/dispatch_test.go
@@ -110,7 +110,8 @@ func TestAggrGroup(t *testing.T) {
 
 		lastCurMtx.Lock()
 		last = current
-		current = time.Now()
+		// Subtract a millisecond to allow for races.
+		current = time.Now().Add(-time.Millisecond)
 		lastCurMtx.Unlock()
 
 		alertsCh <- types.AlertSlice(alerts)
@@ -118,6 +119,15 @@ func TestAggrGroup(t *testing.T) {
 		return true
 	}
 
+	removeEndsAt := func(as types.AlertSlice) types.AlertSlice {
+		for i, a := range as {
+			ac := *a
+			ac.EndsAt = time.Time{}
+			as[i] = &ac
+		}
+		return as
+	}
+
 	// Test regular situation where we wait for group_wait to send out alerts.
 	ag := newAggrGroup(context.Background(), lset, route, nil, log.NewNopLogger())
 	go ag.run(ntfy)
@@ -129,10 +139,13 @@ func TestAggrGroup(t *testing.T) {
 		t.Fatalf("expected initial batch after group_wait")
 
 	case batch := <-alertsCh:
-		if s := time.Since(last); s < opts.GroupWait {
+		lastCurMtx.Lock()
+		s := time.Since(last)
+		lastCurMtx.Unlock()
+		if s < opts.GroupWait {
 			t.Fatalf("received batch too early after %v", s)
 		}
-		exp := types.AlertSlice{a1}
+		exp := removeEndsAt(types.AlertSlice{a1})
 		sort.Sort(batch)
 
 		if !reflect.DeepEqual(batch, exp) {
@@ -149,10 +162,13 @@ func TestAggrGroup(t *testing.T) {
 			t.Fatalf("expected new batch after group interval but received none")
 
 		case batch := <-alertsCh:
-			if s := time.Since(last); s < opts.GroupInterval {
+			lastCurMtx.Lock()
+			s := time.Since(last)
+			lastCurMtx.Unlock()
+			if s < opts.GroupInterval {
 				t.Fatalf("received batch too early after %v", s)
 			}
-			exp := types.AlertSlice{a1, a3}
+			exp := removeEndsAt(types.AlertSlice{a1, a3})
 			sort.Sort(batch)
 
 			if !reflect.DeepEqual(batch, exp) {
@@ -179,7 +195,7 @@ func TestAggrGroup(t *testing.T) {
 		t.Fatalf("expected immediate alert but received none")
 
 	case batch := <-alertsCh:
-		exp := types.AlertSlice{a1, a2}
+		exp := removeEndsAt(types.AlertSlice{a1, a2})
 		sort.Sort(batch)
 
 		if !reflect.DeepEqual(batch, exp) {
@@ -202,7 +218,7 @@ func TestAggrGroup(t *testing.T) {
 			if s < opts.GroupInterval {
 				t.Fatalf("received batch too early after %v", s)
 			}
-			exp := types.AlertSlice{a1, a2, a3}
+			exp := removeEndsAt(types.AlertSlice{a1, a2, a3})
 			sort.Sort(batch)
 
 			if !reflect.DeepEqual(batch, exp) {
@@ -224,7 +240,10 @@ func TestAggrGroup(t *testing.T) {
 		t.Fatalf("expected new batch after group interval but received none")
 
 	case batch := <-alertsCh:
-		if s := time.Since(last); s < opts.GroupInterval {
+		lastCurMtx.Lock()
+		s := time.Since(last)
+		lastCurMtx.Unlock()
+		if s < opts.GroupInterval {
 			t.Fatalf("received batch too early after %v", s)
 		}
 		sort.Sort(batch)