diff --git a/main.go b/main.go
index 0f63f8da5..300bb79b5 100644
--- a/main.go
+++ b/main.go
@@ -74,7 +74,7 @@ type prometheus struct {
 	compactionTimer *time.Ticker
 	deletionTimer   *time.Ticker
 
-	curationSema             chan bool
+	curationSema             chan struct{}
 	stopBackgroundOperations chan bool
 
 	unwrittenSamples chan *extraction.Result
@@ -101,17 +101,22 @@ func (p *prometheus) interruptHandler() {
 
 func (p *prometheus) compact(olderThan time.Duration, groupSize int) error {
 	select {
-	case p.curationSema <- true:
+	case s, ok := <-p.curationSema:
+		if !ok {
+			glog.Warning("Prometheus is shutting down; no more curation runs are allowed.")
+			return nil
+		}
+
+		defer func() {
+			p.curationSema <- s
+		}()
+
 	default:
 		glog.Warningf("Deferred compaction for %s and %s due to existing operation.", olderThan, groupSize)
 
 		return nil
 	}
 
-	defer func() {
-		<-p.curationSema
-	}()
-
 	processor := metric.NewCompactionProcessor(&metric.CompactionProcessorOptions{
 		MaximumMutationPoolBatch: groupSize * 3,
 		MinimumGroupSize:         groupSize,
@@ -130,7 +135,16 @@ func (p *prometheus) compact(olderThan time.Duration, groupSize int) error {
 
 func (p *prometheus) delete(olderThan time.Duration, batchSize int) error {
 	select {
-	case p.curationSema <- true:
+	case s, ok := <-p.curationSema:
+		if !ok {
+			glog.Warning("Prometheus is shutting down; no more curation runs are allowed.")
+			return nil
+		}
+
+		defer func() {
+			p.curationSema <- s
+		}()
+
 	default:
 		glog.Warningf("Deferred deletion for %s due to existing operation.", olderThan)
 
@@ -153,10 +167,7 @@ func (p *prometheus) delete(olderThan time.Duration, batchSize int) error {
 }
 
 func (p *prometheus) close() {
-	select {
-	case p.curationSema <- true:
-	default:
-	}
+	close(p.curationSema)
 
 	if p.compactionTimer != nil {
 		p.compactionTimer.Stop()
@@ -291,7 +302,7 @@ func main() {
 		deletionTimer: deletionTimer,
 
 		curationState: prometheusStatus,
-		curationSema:  make(chan bool, 1),
+		curationSema:  make(chan struct{}, 1),
 
 		unwrittenSamples: unwrittenSamples,
 
@@ -305,6 +316,8 @@ func main() {
 	}
 	defer prometheus.close()
 
+	prometheus.curationSema <- struct{}{}
+
 	storageStarted := make(chan bool)
 	go ts.Serve(storageStarted)
 	<-storageStarted