diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..d08a464
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module github.com/Pexeso/orderedmap
+
+go 1.17
diff --git a/orderedmap.go b/orderedmap.go
index cf8db2a..3ce83a2 100644
--- a/orderedmap.go
+++ b/orderedmap.go
@@ -3,19 +3,19 @@ package orderedmap
 import (
 	"bytes"
 	"encoding/json"
-	"errors"
 	"sort"
 	"strings"
 )
 
-var NoValueError = errors.New("No value for this key")
-
 type KeyIndex struct {
 	Key   string
 	Index int
 }
+
 type ByIndex []KeyIndex
 
+var _ sort.Interface = &ByIndex{}
+
 func (a ByIndex) Len() int           { return len(a) }
 func (a ByIndex) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
 func (a ByIndex) Less(i, j int) bool { return a[i].Index < a[j].Index }
@@ -38,6 +38,8 @@ type ByPair struct {
 	LessFunc func(a *Pair, j *Pair) bool
 }
 
+var _ sort.Interface = &ByPair{}
+
 func (a ByPair) Len() int           { return len(a.Pairs) }
 func (a ByPair) Swap(i, j int)      { a.Pairs[i], a.Pairs[j] = a.Pairs[j], a.Pairs[i] }
 func (a ByPair) Less(i, j int) bool { return a.LessFunc(a.Pairs[i], a.Pairs[j]) }
@@ -94,12 +96,12 @@ func (o *OrderedMap) Keys() []string {
 	return o.keys
 }
 
-// SortKeys Sort the map keys using your sort func
+// SortKeys sorts the map keys using your sort func
 func (o *OrderedMap) SortKeys(sortFunc func(keys []string)) {
 	sortFunc(o.keys)
 }
 
-// Sort Sort the map using your sort func
+// Sort sorts the map using your sort func
 func (o *OrderedMap) Sort(lessFunc func(a *Pair, b *Pair) bool) {
 	pairs := make([]*Pair, len(o.keys))
 	for i, key := range o.keys {
@@ -113,25 +115,32 @@ func (o *OrderedMap) Sort(lessFunc func(a *Pair, b *Pair) bool) {
 	}
 }
 
+var _ json.Unmarshaler = &OrderedMap{}
+
+// UnmarshalJSON implements the json.Unmarshaler interface for OrderedMap.
 func (o *OrderedMap) UnmarshalJSON(b []byte) error {
 	if o.values == nil {
 		o.values = map[string]interface{}{}
 	}
-	var err error
-	err = mapStringToOrderedMap(string(b), o)
-	if err != nil {
-		return err
-	}
-	return nil
+	return mapStringToOrderedMap(string(b), o)
+}
+
+func unmarshalJSON(s string, v interface{}) error {
+	r := strings.NewReader(s)
+	decoder := json.NewDecoder(r)
+	// This option ensures that
+	decoder.UseNumber()
+	return decoder.Decode(v)
 }
 
 func mapStringToOrderedMap(s string, o *OrderedMap) error {
 	// parse string into map
 	m := map[string]interface{}{}
-	err := json.Unmarshal([]byte(s), &m)
+	err := unmarshalJSON(s, &m)
 	if err != nil {
 		return err
 	}
+
 	// Get the order of the keys
 	orderedKeys := []KeyIndex{}
 	for k, _ := range m {
@@ -270,14 +279,16 @@ func sliceStringToSliceWithOrderedMaps(valueStr string, newSlice *[]interface{})
 			endItem = endItem + 1
 			continue
 		}
+
 		// if this substring compiles to json, it's the next item
 		possibleItemStr := strings.TrimSpace(itemsStr[startItem:endItem])
 		var possibleItem interface{}
-		err := json.Unmarshal([]byte(possibleItemStr), &possibleItem)
+		err := unmarshalJSON(possibleItemStr, &possibleItem)
 		if err != nil {
 			endItem = endItem + 1
 			continue
 		}
+
 		if possibleItemStr[0] == '{' {
 			// if item is map, convert to orderedmap
 			oo := New()
@@ -314,6 +325,9 @@ func sliceStringToSliceWithOrderedMaps(valueStr string, newSlice *[]interface{})
 	return nil
 }
 
+var _ json.Marshaler = &OrderedMap{}
+
+// MarshalJSON implements the json.Marshaler interface for OrderedMap.
 func (o OrderedMap) MarshalJSON() ([]byte, error) {
 	s := "{"
 	for _, k := range o.keys {
diff --git a/orderedmap_test.go b/orderedmap_test.go
index 6a06899..07b469d 100644
--- a/orderedmap_test.go
+++ b/orderedmap_test.go
@@ -1,8 +1,10 @@
 package orderedmap
 
 import (
+	"bytes"
 	"encoding/json"
 	"fmt"
+	"math"
 	"sort"
 	"strings"
 	"testing"
@@ -395,11 +397,31 @@ func TestUnmarshalJSONStruct(t *testing.T) {
 	x, ok := v.Data.Get("x")
 	if !ok {
 		t.Errorf("missing expected key")
-	} else if x != float64(1) {
+	} else if x != json.Number("1") {
 		t.Errorf("unexpected value: %#v", x)
 	}
 }
 
+func TestRemarshalJSON(t *testing.T) {
+	const input = `{"data":{"x":9007199254740993}}`
+
+	o := New()
+
+	err := json.Unmarshal([]byte(input), &o)
+	if err != nil {
+		t.Fatalf("JSON unmarshal error: %v", err)
+	}
+
+	marshalled, err := json.Marshal(o)
+	if err != nil {
+		t.Errorf("Marshal failed: %v", err)
+	}
+
+	if string(marshalled) != input {
+		t.Errorf("unexpected value: %s instead of %s", marshalled, input)
+	}
+}
+
 func TestOrderedMap_SortKeys(t *testing.T) {
 	s := `
 {
@@ -438,7 +460,15 @@ func TestOrderedMap_Sort(t *testing.T) {
 	o := New()
 	json.Unmarshal([]byte(s), &o)
 	o.Sort(func(a *Pair, b *Pair) bool {
-		return a.value.(float64) > b.value.(float64)
+		na, err := a.value.(json.Number).Float64()
+		if err != nil {
+			panic(err)
+		}
+		nb, err := b.value.(json.Number).Float64()
+		if err != nil {
+			panic(err)
+		}
+		return na > nb
 	})
 
 	// Check the root keys
@@ -486,3 +516,23 @@ func TestOrderedMap_empty_map(t *testing.T) {
 		t.Error("Got", marshalledStr)
 	}
 }
+
+func TestOrderedMap_uint64_slice_serialization(t *testing.T) {
+	uints := []uint64{math.MaxUint64, math.MaxUint64-100, math.MaxUint64-1000}
+
+	str1 := []byte(fmt.Sprintf(`{"key":[%d,%d,%d]}`, uints[0], uints[1], uints[2]))
+	om := New()
+
+	if err := json.Unmarshal(str1, om); err != nil {
+		t.Fatal(err)
+	}
+
+	str2, err := json.Marshal(om)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !bytes.Equal(str1, str2) {
+		t.Fatalf("%s != %s", str1, str2)
+	}
+}