diff --git a/backend/pool.go b/backend/pool.go
index 29e130d..758e33b 100644
--- a/backend/pool.go
+++ b/backend/pool.go
@@ -59,7 +59,12 @@ func (cp *Pool) Get() (net.Conn, error) {
 	}
 }
 
-func (cp *Pool) Return(c net.Conn) {
+func (cp *Pool) Return(c net.Conn, failed bool) {
+
+	if failed {
+		<-cp.createsem
+		return
+	}
 	select {
 	case cp.connections <- c:
 	default:
diff --git a/backend/writer.go b/backend/writer.go
index 53385ed..1d4481e 100644
--- a/backend/writer.go
+++ b/backend/writer.go
@@ -46,9 +46,7 @@ func (w *MetricWriter) Write(rq prompb.WriteRequest) error {
 	bw := bufio.NewWriter(out)
 	defer func() {
 		bw.Flush()
-		if !fail {
-			w.pool.Return(out)
-		}
+		w.pool.Return(out, fail)
 	}()
 	for _, ts := range rq.Timeseries {
 		if err := w.writeMetrics(bw, &ts); err != nil {