diff --git a/prometheus/metric.go b/prometheus/metric.go
index 5bb7f80..0df1eff 100644
--- a/prometheus/metric.go
+++ b/prometheus/metric.go
@@ -18,13 +18,12 @@ import (
 	"time"
 
 	"github.com/golang/protobuf/proto"
+	"github.com/prometheus/common/model"
 
 	dto "github.com/prometheus/client_model/go"
 )
 
-const separatorByte byte = 255
-
-var separatorByteSlice = []byte{255} // For convenient use with xxhash.
+var separatorByteSlice = []byte{model.SeparatorByte} // For convenient use with xxhash.
 
 // A Metric models a single sample value with its meta data being exported to
 // Prometheus. Implementations of Metric in this package are Gauge, Counter,