diff --git a/model/internal/data/optional.go b/model/internal/data/optional.go
index 0d1b6042f98..b921ed15427 100644
--- a/model/internal/data/optional.go
+++ b/model/internal/data/optional.go
@@ -52,13 +52,20 @@ func (o *OptionalDouble) MarshalTo(dAtA []byte) (n int, err error) {
 	return o.marshalToSizedBuffer(dAtA[:size])
 }
 
-// TODO: implement Unmarshal, MarshalJSON, UnmarshalJSON
+// TODO: implement MarshalJSON, UnmarshalJSON
 
 func (o *OptionalDouble) marshalToSizedBuffer(dAtA []byte) (int, error) {
 	i := len(dAtA)
 	i -= 8
 	encoding_binary.LittleEndian.PutUint64(dAtA[i:], uint64(math.Float64bits(float64(o.DoubleValue))))
 	i--
-	dAtA[i] = 0x21
 	return len(dAtA) - i, nil
 }
+
+func (o *OptionalDouble) Unmarshal(dAtA []byte) error {
+	v := uint64(encoding_binary.LittleEndian.Uint64(dAtA))
+	v2 := float64(math.Float64frombits(v))
+	o.DoubleValue = v2
+	o.isSet = true
+	return nil
+}
diff --git a/model/internal/data/protogen/metrics/v1/metrics.pb.go b/model/internal/data/protogen/metrics/v1/metrics.pb.go
index a1d4ebcd405..15c0ad34f57 100644
--- a/model/internal/data/protogen/metrics/v1/metrics.pb.go
+++ b/model/internal/data/protogen/metrics/v1/metrics.pb.go
@@ -3180,21 +3180,19 @@ func (m *HistogramDataPoint) MarshalToSizedBuffer(dAtA []byte) (int, error) {
 	_ = i
 	var l int
 	_ = l
-	if !m.Min.IsEmpty() {
-		size, err := m.Min.MarshalTo(dAtA[:i])
-		if err != nil {
+	if !m.Max.IsEmpty() {
+		i -= m.Max.Size()
+		if _, err := m.Max.MarshalTo(dAtA[i:]); err != nil {
 			return 0, err
 		}
-		i -= size
-		dAtA[i] = 0x5E
+		dAtA[i] = 0x61
 	}
-	if !m.Max.IsEmpty() {
-		size, err := m.Max.MarshalTo(dAtA[:i])
-		if err != nil {
+	if !m.Min.IsEmpty() {
+		i -= m.Min.Size()
+		if _, err := m.Min.MarshalTo(dAtA[i:]); err != nil {
 			return 0, err
 		}
-		i -= size
-		dAtA[i] = 0x56
+		dAtA[i] = 0x59
 	}
 	if m.Flags != 0 {
 		i = encodeVarintMetrics(dAtA, i, uint64(m.Flags))
@@ -6573,15 +6571,29 @@ func (m *HistogramDataPoint) Unmarshal(dAtA []byte) error {
 				}
 			}
 		case 11:
-			// TODO: unmarshal here
-			if wireType != 0 {
+			if wireType != 1 {
 				return fmt.Errorf("proto: wrong wireType = %d for field Min", wireType)
 			}
+			postIndex := iNdEx + 8
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			if err := m.Min.Unmarshal(dAtA[iNdEx:postIndex]); err != nil {
+				return err
+			}
+			iNdEx = postIndex
 		case 12:
-			// TODO: unmarshal here
-			if wireType != 0 {
+			if wireType != 1 {
 				return fmt.Errorf("proto: wrong wireType = %d for field Max", wireType)
 			}
+			postIndex := iNdEx + 8
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			if err := m.Max.Unmarshal(dAtA[iNdEx:postIndex]); err != nil {
+				return err
+			}
+			iNdEx = postIndex
 		default:
 			iNdEx = preIndex
 			skippy, err := skipMetrics(dAtA[iNdEx:])
diff --git a/model/otlp/pb_test.go b/model/otlp/pb_test.go
index 51fe65049fd..a25cb8e8acb 100644
--- a/model/otlp/pb_test.go
+++ b/model/otlp/pb_test.go
@@ -95,7 +95,7 @@ func TestProtobufMetricsSizerWithOptional(t *testing.T) {
 
 	p := NewProtobufMetricsUnmarshaler()
 	unmarshalled, err := p.UnmarshalMetrics(bytes)
-	assert.Error(t, err)
+	assert.NoError(t, err)
 	assert.Equal(t, metric, unmarshalled.ResourceMetrics().At(0).InstrumentationLibraryMetrics().At(0).Metrics().At(0))
 
 }