diff --git a/pick.go b/pick.go
index 5522627..1241b2f 100644
--- a/pick.go
+++ b/pick.go
@@ -1,7 +1,9 @@
 package pick
 
 import (
+	"bytes"
 	"encoding/json"
+	"io"
 
 	"github.com/moukoublen/pick/cast"
 )
@@ -15,22 +17,27 @@ type Traverser interface {
 	Get(m any, selector []SelectorKey) (any, error)
 }
 
-func Wrap(data any) *Picker {
-	caster := cast.NewCaster()
-	formatter := DefaultSelectorFormat{}
-	return NewPicker(data, NewDefaultTraverser(caster), caster, formatter)
+func WrapJSON(js []byte) (*Picker, error) {
+	return WrapReaderJSON(bytes.NewReader(js))
 }
 
-func WrapJSON(js []byte) (*Picker, error) {
+func WrapReaderJSON(r io.Reader) (*Picker, error) {
+	d := json.NewDecoder(r)
+	return WrapDecoder(d)
+}
+
+func WrapDecoder(decoder interface{ Decode(destination any) error }) (*Picker, error) {
 	m := map[string]any{}
-	err := json.Unmarshal(js, &m)
-	if err != nil {
+	if err := decoder.Decode(&m); err != nil {
 		return nil, err
 	}
 
+	return Wrap(m), nil
+}
+
+func Wrap(data any) *Picker {
 	caster := cast.NewCaster()
-	formatter := DefaultSelectorFormat{}
-	return NewPicker(m, NewDefaultTraverser(caster), caster, formatter), nil
+	return NewPicker(data, NewDefaultTraverser(caster), caster, DefaultSelectorFormat{})
 }
 
 type Picker struct {
@@ -40,12 +47,12 @@ type Picker struct {
 	selectorFormat SelectorFormat
 }
 
-func NewPicker(inner any, t Traverser, c Caster, selectorFormat SelectorFormat) *Picker {
+func NewPicker(data any, t Traverser, c Caster, s SelectorFormat) *Picker {
 	return &Picker{
-		inner:          inner,
+		inner:          data,
 		traverser:      t,
 		caster:         c,
-		selectorFormat: selectorFormat,
+		selectorFormat: s,
 	}
 }
 
diff --git a/pick_test.go b/pick_test.go
index 8fe8342..57e6dff 100644
--- a/pick_test.go
+++ b/pick_test.go
@@ -2,8 +2,8 @@ package pick
 
 import (
 	"embed"
-	"encoding/json"
 	"fmt"
+	"io/fs"
 	"path/filepath"
 	"reflect"
 	"testing"
@@ -115,7 +115,7 @@ func TestString(t *testing.T) {
 //go:embed internal/testingx/testdata
 var testData embed.FS
 
-func loadTestData(t *testing.T, filename string, decodeInto any) {
+func loadTestData(t *testing.T, filename string) (fs.File, error) {
 	t.Helper()
 
 	path := filepath.Join("internal", "testingx", "testdata", filename)
@@ -124,17 +124,21 @@ func loadTestData(t *testing.T, filename string, decodeInto any) {
 		t.Fatalf("error during testdate file opening %s", err.Error())
 	}
 
-	if err := json.NewDecoder(f).Decode(decodeInto); err != nil {
-		t.Fatalf("error during testdate file decoding %s", err.Error())
-	}
+	return f, nil
 }
 
 func TestNasaDataFile(t *testing.T) {
 	t.Parallel()
-	inner := map[string]any{}
-	loadTestData(t, "nasa.json", &inner)
 
-	ob := Wrap(inner)
+	file, err := loadTestData(t, "nasa.json")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	ob, err := WrapReaderJSON(file)
+	if err != nil {
+		t.Fatal(err)
+	}
 
 	tests := []struct {
 		accessFn      any