diff --git a/prometheus/graphite/bridge.go b/prometheus/graphite/bridge.go
index 09b7c9edd..09c31b5cd 100644
--- a/prometheus/graphite/bridge.go
+++ b/prometheus/graphite/bridge.go
@@ -197,14 +197,16 @@ func writeMetrics(w io.Writer, mfs []*dto.MetricFamily, useTags bool, prefix str
 
 	buf := bufio.NewWriter(w)
 	for _, s := range vec {
-		for _, c := range prefix {
-			if _, err := buf.WriteRune(c); err != nil {
+		if prefix != "" {
+			for _, c := range prefix {
+				if _, err := buf.WriteRune(c); err != nil {
+					return err
+				}
+			}
+			if err := buf.WriteByte('.'); err != nil {
 				return err
 			}
 		}
-		if err := buf.WriteByte('.'); err != nil {
-			return err
-		}
 		if err := writeMetric(buf, s.Metric, useTags); err != nil {
 			return err
 		}
diff --git a/prometheus/graphite/bridge_test.go b/prometheus/graphite/bridge_test.go
index ae418afb5..df0cfff3f 100644
--- a/prometheus/graphite/bridge_test.go
+++ b/prometheus/graphite/bridge_test.go
@@ -101,6 +101,7 @@ func testWriteSummary(t *testing.T, useTags bool) {
 		{prefix: "prefix"},
 		{prefix: "pre/fix"},
 		{prefix: "pre.fix"},
+		{prefix: ""},
 	}
 
 	var (
@@ -141,10 +142,15 @@ func testWriteSummary(t *testing.T, useTags bool) {
 			t.Fatalf("error: %v", err)
 		}
 
-		wantWithPrefix := fmt.Sprintf(want,
-			tc.prefix, tc.prefix, tc.prefix, tc.prefix, tc.prefix,
-			tc.prefix, tc.prefix, tc.prefix, tc.prefix, tc.prefix,
-		)
+		var wantWithPrefix string
+		if tc.prefix == "" {
+			wantWithPrefix = strings.ReplaceAll(want, "%s.", "")
+		} else {
+			wantWithPrefix = fmt.Sprintf(want,
+				tc.prefix, tc.prefix, tc.prefix, tc.prefix, tc.prefix,
+				tc.prefix, tc.prefix, tc.prefix, tc.prefix, tc.prefix,
+			)
+		}
 
 		got := buf.String()