@@ -286,15 +286,16 @@ func (h *Bitmap) validateOrdinal(ordinal uint64) error {

 // MarshalBinary encodes h into a binary representation.

 func (h *Bitmap) MarshalBinary() ([]byte, error) {

-	ba := make([]byte, 16)

-	binary.BigEndian.PutUint64(ba[0:], h.bits)

-	binary.BigEndian.PutUint64(ba[8:], h.unselected)

 	bm, err := h.head.toByteArray()

 	if err != nil {

 		return nil, fmt.Errorf("failed to serialize head: %v", err)

 	}

-	ba = append(ba, bm...)

+	// Pre-allocate capacity for "bits" and "unselected" (16 bytes) and head.

+	ba := make([]byte, 0, 16+len(bm))

+	ba = binary.BigEndian.AppendUint64(ba, h.bits)

+	ba = binary.BigEndian.AppendUint64(ba, h.unselected)

+	ba = append(ba, bm...)

 	return ba, nil

 }