diff --git a/.gitignore b/.gitignore
index 24e5b0a..c295d16 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
 .build
+build
diff --git a/cmd/args.go b/cmd/args.go
index efeaa4d..072e6e9 100644
--- a/cmd/args.go
+++ b/cmd/args.go
@@ -41,6 +41,7 @@ type options struct {
 	flushInterval time.Duration
 	backend       backends.StorageBackend
 	backendRoot   string
+	prefix        string
 
 	verbosity log.Level
 }
diff --git a/cmd/root.go b/cmd/root.go
index 3391566..dc9bb2a 100644
--- a/cmd/root.go
+++ b/cmd/root.go
@@ -58,6 +58,13 @@ func rootCmd() *cobra.Command {
 		"root path/location for the specified backend (e.g. bucket name for AWS S3)",
 	)
 
+	root.PersistentFlags().StringVar(
+		&opts.prefix,
+		prefixFlag,
+		"",
+		"directory prefix for saving parquet files",
+	)
+
 	root.PersistentFlags().VarP(
 		enumflag.New(&opts.verbosity, verbosityFlag, logLevelIDs, enumflag.EnumCaseInsensitive),
 		verbosityFlag,
diff --git a/cmd/server.go b/cmd/server.go
index f67d961..31b8a90 100644
--- a/cmd/server.go
+++ b/cmd/server.go
@@ -117,8 +117,17 @@ func (self *promserver) sendTimeseries(ctx context.Context, timeserieses []promp
 		var ok bool
 
 		nameLabel, _ := lo.Find(ts.Labels, func(i prompb.Label) bool { return i.Name == model.MetricNameLabel })
-		prefixLabel, _ := lo.Find(ts.Labels, func(i prompb.Label) bool { return i.Name == prefixLabelKey })
-		channelName := prefixLabel.Value + "/" + nameLabel.Value
+		prefixLabel, prefixFound := lo.Find(ts.Labels, func(i prompb.Label) bool { return i.Name == prefixLabelKey })
+
+		prefix := prefixLabel.Value
+		if !prefixFound || prefix == "" {
+			prefix = self.opts.prefix
+		}
+
+		channelName := prefix + "/" + nameLabel.Value
+		if prefix == "" {
+			channelName = nameLabel.Value
+		}
 
 		log.Debugf("received timeseries data for %s", channelName)
 
diff --git a/cmd/server_test.go b/cmd/server_test.go
index d4053d7..3e38ce8 100644
--- a/cmd/server_test.go
+++ b/cmd/server_test.go
@@ -121,3 +121,69 @@ func TestSpawnWriter(t *testing.T) {
 	assert.Nil(t, err)
 	assert.Contains(t, srv.channels, channelName)
 }
+
+func TestSendTimeseriesWithCLIPrefix(t *testing.T) {
+	cliPrefix := "cli-prefix"
+	srv := newServer(&options{prefix: cliPrefix})
+	expectedChannelName := cliPrefix + "/" + metricName
+	srv.channels[expectedChannelName] = make(chan prompb.TimeSeries)
+
+	ts := prompb.TimeSeries{
+		Labels: []prompb.Label{
+			{
+				Name:  model.MetricNameLabel,
+				Value: metricName,
+			},
+			{
+				Name:  "foo",
+				Value: "bar",
+			},
+		},
+		Samples: []prompb.Sample{
+			{
+				Value:     1.0,
+				Timestamp: 0,
+			},
+		},
+	}
+
+	go func() {
+		err := srv.sendTimeseries(context.TODO(), []prompb.TimeSeries{ts})
+		assert.Nil(t, err)
+	}()
+
+	val := <-srv.channels[expectedChannelName]
+	assert.Equal(t, ts, val)
+}
+
+func TestSendTimeseriesWithoutPrefix(t *testing.T) {
+	srv := newServer(&options{})
+	srv.channels[metricName] = make(chan prompb.TimeSeries)
+
+	ts := prompb.TimeSeries{
+		Labels: []prompb.Label{
+			{
+				Name:  model.MetricNameLabel,
+				Value: metricName,
+			},
+			{
+				Name:  "foo",
+				Value: "bar",
+			},
+		},
+		Samples: []prompb.Sample{
+			{
+				Value:     1.0,
+				Timestamp: 0,
+			},
+		},
+	}
+
+	go func() {
+		err := srv.sendTimeseries(context.TODO(), []prompb.TimeSeries{ts})
+		assert.Nil(t, err)
+	}()
+
+	val := <-srv.channels[metricName]
+	assert.Equal(t, ts, val)
+}