diff --git a/tsweb/tsweb.go b/tsweb/tsweb.go
index 8ba1a52a7..a42f59dcd 100644
--- a/tsweb/tsweb.go
+++ b/tsweb/tsweb.go
@@ -474,7 +474,7 @@ func writePromExpVar(w io.Writer, prefix string, kv expvar.KeyValue) {
 			label, key = a, b
 		}
 	}
-	name := prefix + key
+	name := strings.ReplaceAll(prefix+key, "-", "_")
 
 	switch v := kv.Value.(type) {
 	case PrometheusVar:
diff --git a/tsweb/tsweb_test.go b/tsweb/tsweb_test.go
index a38b671c9..d571a3773 100644
--- a/tsweb/tsweb_test.go
+++ b/tsweb/tsweb_test.go
@@ -359,6 +359,12 @@ func TestVarzHandler(t *testing.T) {
 			new(expvar.Int),
 			"# TYPE foo counter\nfoo 0\n",
 		},
+		{
+			"dash_in_metric_name",
+			"counter_foo-bar",
+			new(expvar.Int),
+			"# TYPE foo_bar counter\nfoo_bar 0\n",
+		},
 		{
 			"int_with_type_counter",
 			"counter_foo",