diff --git a/environment.go b/environment.go
index c3e7d41..cb2e832 100644
--- a/environment.go
+++ b/environment.go
@@ -9,6 +9,8 @@ import (
 	"strconv"
 	"sync"
 	"sync/atomic"
+
+	"github.com/gowool/extends-template/internal"
 )
 
 const (
@@ -55,8 +57,8 @@ func (e *Environment) Delims(left, right string) *Environment {
 
 	e.left = left
 	e.right = right
-	e.reExtends = ReExtends(left, right)
-	e.reTemplate = ReTemplate(left, right)
+	e.reExtends = internal.ReExtends(left, right)
+	e.reTemplate = internal.ReTemplate(left, right)
 	e.updateHash()
 
 	return e
@@ -137,10 +139,10 @@ func (e *Environment) updateHash() {
 		buf.WriteString(name)
 	}
 
-	e.hash.Store(hash(buf.Bytes()))
+	e.hash.Store(internal.Hash(buf.Bytes()))
 	e.templates = &sync.Map{}
 }
 
 func (e *Environment) key(name string) string {
-	return hash(toBytes(fmt.Sprintf("%s:%s", name, e.hash.Load())))
+	return internal.Hash(internal.Bytes(fmt.Sprintf("%s:%s", name, e.hash.Load())))
 }
diff --git a/go.mod b/go.mod
index 930fc24..bfa99c8 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module github.com/gowool/extends-template
 
-go 1.21
+go 1.22.0
 
 require github.com/stretchr/testify v1.8.4
 
diff --git a/common.go b/internal/common.go
similarity index 51%
rename from common.go
rename to internal/common.go
index b0bf583..359764a 100644
--- a/common.go
+++ b/internal/common.go
@@ -1,11 +1,10 @@
-package et
+package internal
 
 import (
 	"crypto/sha256"
 	"fmt"
 	"reflect"
 	"regexp"
-	"unsafe"
 )
 
 const (
@@ -21,22 +20,7 @@ func ReTemplate(left, right string) *regexp.Regexp {
 	return regexp.MustCompile(fmt.Sprintf(templatePattern, left, right))
 }
 
-func merge(left error, right error) error {
-	switch {
-	case left == nil:
-		return right
-	case right == nil:
-		return left
-	}
-
-	return fmt.Errorf("%w; %w", left, right)
-}
-
-func errorf(right error, format string, a ...any) error {
-	return merge(fmt.Errorf(format, a...), right)
-}
-
-func typeName(i any) string {
+func TypeName(i any) string {
 	t := reflect.TypeOf(i)
 
 	for t.Kind() == reflect.Ptr {
@@ -46,14 +30,6 @@ func typeName(i any) string {
 	return t.Name()
 }
 
-func toBytes(s string) []byte {
-	return unsafe.Slice(unsafe.StringData(s), len(s))
-}
-
-func toString(b []byte) string {
-	return *(*string)(unsafe.Pointer(&b))
-}
-
-func hash(data []byte) string {
+func Hash(data []byte) string {
 	return fmt.Sprintf("%x", sha256.Sum256(data))
 }
diff --git a/internal/unsafe.go b/internal/unsafe.go
new file mode 100644
index 0000000..4f8b113
--- /dev/null
+++ b/internal/unsafe.go
@@ -0,0 +1,11 @@
+package internal
+
+import "unsafe"
+
+func Bytes(s string) []byte {
+	return unsafe.Slice(unsafe.StringData(s), len(s))
+}
+
+func String(b []byte) string {
+	return *(*string)(unsafe.Pointer(&b))
+}
diff --git a/loader_chain.go b/loader_chain.go
index 19e5ae4..6a3d3d5 100644
--- a/loader_chain.go
+++ b/loader_chain.go
@@ -2,8 +2,11 @@ package et
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"sync"
+
+	"github.com/gowool/extends-template/internal"
 )
 
 var _ Loader = (*ChainLoader)(nil)
@@ -83,16 +86,16 @@ func (l *ChainLoader) loop(ctx context.Context, name string, fn func(loader Load
 
 	for _, loader := range l.loaders {
 		if ok, err1 := loader.Exists(ctx, name); !ok {
-			err = merge(err, err1)
+			err = errors.Join(err, err1)
 			continue
 		}
 
 		if r, err1 := fn(loader); err1 == nil {
 			return r, nil
 		} else {
-			err = merge(err, fmt.Errorf("[%s]: %w", typeName(loader), err1))
+			err = errors.Join(err, fmt.Errorf("[%s]: %w", internal.TypeName(loader), err1))
 		}
 	}
 
-	return nil, errorf(err, ErrNotDefinedFormat, name)
+	return nil, errors.Join(fmt.Errorf(ErrNotDefinedFormat, name), err)
 }
diff --git a/loader_filesystem.go b/loader_filesystem.go
index a588ff2..73b1880 100644
--- a/loader_filesystem.go
+++ b/loader_filesystem.go
@@ -2,6 +2,7 @@ package et
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"io/fs"
 	"path/filepath"
@@ -101,7 +102,7 @@ func (l *FilesystemLoader) SetPaths(namespace string, paths ...string) error {
 
 	var err error
 	for _, p := range paths {
-		err = merge(err, l.add(namespace, p))
+		err = errors.Join(err, l.add(namespace, p))
 	}
 	return err
 }
@@ -199,9 +200,9 @@ func (l *FilesystemLoader) path(p string) (string, error) {
 	p = strings.Trim(l.normalize(p), sep)
 
 	if stat, err := fs.Stat(l.fsys, p); err != nil {
-		return p, errorf(err, ErrDirNotExistsFormat, p)
+		return p, errors.Join(fmt.Errorf(ErrDirNotExistsFormat, p), err)
 	} else if !stat.IsDir() {
-		return p, errorf(nil, ErrDirNotExistsFormat, p)
+		return p, fmt.Errorf(ErrDirNotExistsFormat, p)
 	}
 
 	return p, nil
diff --git a/loader_memory.go b/loader_memory.go
index 91d3934..56cbc6f 100644
--- a/loader_memory.go
+++ b/loader_memory.go
@@ -2,6 +2,7 @@ package et
 
 import (
 	"context"
+	"fmt"
 	"sync"
 )
 
@@ -31,7 +32,7 @@ func (l *MemoryLoader) Get(_ context.Context, name string) (*Source, error) {
 	if code, ok := l.templates.Load(name); ok {
 		return &Source{Code: code.([]byte), Name: name}, nil
 	}
-	return nil, errorf(nil, ErrNotDefinedFormat, name)
+	return nil, fmt.Errorf(ErrNotDefinedFormat, name)
 }
 
 func (l *MemoryLoader) IsFresh(ctx context.Context, name string, _ int64) (bool, error) {
@@ -42,5 +43,5 @@ func (l *MemoryLoader) Exists(_ context.Context, name string) (bool, error) {
 	if _, ok := l.templates.Load(name); ok {
 		return true, nil
 	}
-	return false, errorf(nil, ErrNotDefinedFormat, name)
+	return false, fmt.Errorf(ErrNotDefinedFormat, name)
 }
diff --git a/node.go b/node.go
index 06d2de1..244677d 100644
--- a/node.go
+++ b/node.go
@@ -5,6 +5,8 @@ import (
 	"context"
 	"html/template"
 	"path"
+
+	"github.com/gowool/extends-template/internal"
 )
 
 type Handler func(ctx context.Context, node *Node, namespace string) error
@@ -52,20 +54,20 @@ func (n *Node) Init(ctx context.Context) (err error) {
 
 	if extends := n.w.reExtends.FindAllSubmatch(n.Source.Code, -1); len(extends) > 0 {
 		n.Source.Code = n.w.reExtends.ReplaceAll(n.Source.Code, []byte{})
-		if err = NewNode(toString(extends[0][1]), n.w, n).Init(ctx); err != nil {
+		if err = NewNode(internal.String(extends[0][1]), n.w, n).Init(ctx); err != nil {
 			return
 		}
 	}
 
 	if includes := n.w.reTemplates.FindAllSubmatch(n.Source.Code, -1); len(includes) > 0 {
 		for _, tpl := range includes {
-			include := NewNode(toString(tpl[1]), n.w, nil)
+			include := NewNode(internal.String(tpl[1]), n.w, nil)
 			if err = include.Init(ctx); err != nil {
 				return
 			}
 			n.Includes = append(n.Includes, include)
 			if n.w.ns != "" && '@' == n.w.ns[0] && '@' != rune(tpl[1][0]) {
-				n.Source.Code = bytes.Replace(n.Source.Code, tpl[1], append(toBytes(n.w.ns), tpl[1]...), 1)
+				n.Source.Code = bytes.Replace(n.Source.Code, tpl[1], append(internal.Bytes(n.w.ns), tpl[1]...), 1)
 			}
 		}
 	}
@@ -80,7 +82,7 @@ func (n *Node) Init(ctx context.Context) (err error) {
 }
 
 func (n *Node) Parse(t *template.Template) error {
-	if _, err := t.Parse(toString(n.Source.Code)); err != nil {
+	if _, err := t.Parse(internal.String(n.Source.Code)); err != nil {
 		return err
 	}
 
diff --git a/template_wrapper_test.go b/template_wrapper_test.go
index 4200e3f..6dfb971 100644
--- a/template_wrapper_test.go
+++ b/template_wrapper_test.go
@@ -12,6 +12,7 @@ import (
 	"github.com/stretchr/testify/assert"
 
 	et "github.com/gowool/extends-template"
+	"github.com/gowool/extends-template/internal"
 )
 
 const (
@@ -83,8 +84,8 @@ func TestTemplateWrapper_IsFresh(t *testing.T) {
 			template.New(name),
 			wrapLoader{t: s.t},
 			s.handlers,
-			et.ReExtends("{{", "}}"),
-			et.ReTemplate("{{", "}}"))
+			internal.ReExtends("{{", "}}"),
+			internal.ReTemplate("{{", "}}"))
 
 		isFresh := wrapper.IsFresh(context.TODO())
 
@@ -122,8 +123,8 @@ func TestTemplateWrapper_Parse(t *testing.T) {
 			template.New(name),
 			wrapLoader{},
 			s.handlers,
-			et.ReExtends("{{", "}}"),
-			et.ReTemplate("{{", "}}"),
+			internal.ReExtends("{{", "}}"),
+			internal.ReTemplate("{{", "}}"),
 			"@main/global.html",
 		)