diff --git a/expfmt/openmetrics_create_test.go b/expfmt/openmetrics_create_test.go
index be8e77fb..718f623a 100644
--- a/expfmt/openmetrics_create_test.go
+++ b/expfmt/openmetrics_create_test.go
@@ -34,7 +34,7 @@ func TestCreateOpenMetrics(t *testing.T) {
 
 	var scenarios = []struct {
 		in       *dto.MetricFamily
-		withUnit ToOpenMetricsOption
+		withUnit bool
 		out      string
 	}{
 		// 0: Counter, timestamp given, no _total suffix.
@@ -236,6 +236,7 @@ summary_name_count{name_1="value 1",name_2="value 2"} 4711
 				Name: proto.String("request_duration_microseconds"),
 				Help: proto.String("The response latency."),
 				Type: dto.MetricType_HISTOGRAM.Enum(),
+				Unit: proto.String("microseconds"),
 				Metric: []*dto.Metric{
 					&dto.Metric{
 						Histogram: &dto.Histogram{
@@ -267,8 +268,10 @@ summary_name_count{name_1="value 1",name_2="value 2"} 4711
 					},
 				},
 			},
+			withUnit: true,
 			out: `# HELP request_duration_microseconds The response latency.
 # TYPE request_duration_microseconds histogram
+# UNIT request_duration_microseconds microseconds
 request_duration_microseconds_bucket{le="100.0"} 123
 request_duration_microseconds_bucket{le="120.0"} 412
 request_duration_microseconds_bucket{le="144.0"} 592
@@ -284,6 +287,7 @@ request_duration_microseconds_count 2693
 				Name: proto.String("request_duration_microseconds"),
 				Help: proto.String("The response latency."),
 				Type: dto.MetricType_HISTOGRAM.Enum(),
+				Unit: proto.String("microseconds"),
 				Metric: []*dto.Metric{
 					&dto.Metric{
 						Histogram: &dto.Histogram{
@@ -429,8 +433,10 @@ foos_total 42.0
 				Unit:   proto.String("seconds"),
 				Metric: []*dto.Metric{},
 			},
+			withUnit: true,
 			out: `# HELP name_seconds doc string
 # TYPE name_seconds counter
+# UNIT name_seconds seconds
 `,
 		},
 		// 10: Histogram plus unit.
@@ -482,58 +488,7 @@ request_duration_microseconds_sum 1.7560473e+06
 request_duration_microseconds_count 2693
 `,
 		},
-	}
-
-	for i, scenario := range scenarios {
-		out := bytes.NewBuffer(make([]byte, 0, len(scenario.out)))
-
-		n, err := MetricFamilyToOpenMetrics(out, scenario.in)
-		if err != nil {
-			t.Errorf("%d. error: %s", i, err)
-			continue
-		}
-		if expected, got := len(scenario.out), n; expected != got {
-			t.Errorf(
-				"%d. expected %d bytes written, got %d",
-				i, expected, got,
-			)
-		}
-		if expected, got := scenario.out, out.String(); expected != got {
-			t.Errorf(
-				"%d. expected out=%q, got %q",
-				i, expected, got,
-			)
-		}
-	}
-
-}
-
-func TestCreateOpenMatricsWithUnit(t *testing.T) {
-	openMetricsTimestamp := timestamppb.New(time.Unix(12345, 600000000))
-	if err := openMetricsTimestamp.CheckValid(); err != nil {
-		t.Error(err)
-	}
-
-	var scenarios = []struct {
-		in       *dto.MetricFamily
-		withUnit ToOpenMetricsOption
-		out      string
-	}{
-		// 1: No metric plus unit.
-		{
-			in: &dto.MetricFamily{
-				Name:   proto.String("name_seconds_total"),
-				Help:   proto.String("doc string"),
-				Type:   dto.MetricType_COUNTER.Enum(),
-				Unit:   proto.String("seconds"),
-				Metric: []*dto.Metric{},
-			},
-			out: `# HELP name_seconds doc string
-# TYPE name_seconds counter
-# UNIT name_seconds seconds
-`,
-		},
-		// 2: No metric plus unit no unit in name.
+		// 11: No metric unit opted in no unit in name
 		{
 			in: &dto.MetricFamily{
 				Name:   proto.String("name_total"),
@@ -542,44 +497,21 @@ func TestCreateOpenMatricsWithUnit(t *testing.T) {
 				Unit:   proto.String("seconds"),
 				Metric: []*dto.Metric{},
 			},
-			out: `# HELP name_seconds doc string
-# TYPE name_seconds counter
-# UNIT name_seconds seconds
-`,
-		},
-		// 3: No metric plus unit wrong unit in name. // Can this happen at all?
-		{
-			in: &dto.MetricFamily{
-				Name:   proto.String("name_milliseconds_total"),
-				Help:   proto.String("doc string"),
-				Type:   dto.MetricType_COUNTER.Enum(),
-				Unit:   proto.String("seconds"),
-				Metric: []*dto.Metric{},
-			},
-			out: `# HELP name_milliseconds_seconds doc string
-# TYPE name_milliseconds_seconds counter
-# UNIT name_milliseconds_seconds seconds
-`,
-		},
-		// 3: No metric plus unit already in name.
-		{
-			in: &dto.MetricFamily{
-				Name:   proto.String("name_seconds_total"),
-				Help:   proto.String("doc string"),
-				Type:   dto.MetricType_COUNTER.Enum(),
-				Unit:   proto.String("seconds"),
-				Metric: []*dto.Metric{},
-			},
+			withUnit: true,
 			out: `# HELP name_seconds doc string
 # TYPE name_seconds counter
 # UNIT name_seconds seconds
 `,
 		},
 	}
+
 	for i, scenario := range scenarios {
 		out := bytes.NewBuffer(make([]byte, 0, len(scenario.out)))
-
-		n, err := MetricFamilyToOpenMetrics(out, scenario.in, ToOpenMetricsWithUnit())
+		opts := []ToOpenMetricsOption{}
+		if scenario.withUnit {
+			opts = append(opts, ToOpenMetricsWithUnit())
+		}
+		n, err := MetricFamilyToOpenMetrics(out, scenario.in, opts...)
 		if err != nil {
 			t.Errorf("%d. error: %s", i, err)
 			continue