diff --git a/config.go b/config.go
index 9dc425ea..934d2038 100644
--- a/config.go
+++ b/config.go
@@ -30,11 +30,17 @@ type Unmarshaler interface {
 
 // New returns a Config with the given Option(s).
 func New(opts ...Option) (Config, error) {
-	option := apply(opts)
-	config := option.Config
-	config.values = &provider{values: make(map[string]any)}
-	config.providers = make([]*provider, 0, len(option.loaders))
-	config.onChanges = &onChanges{onChanges: make(map[string][]func(Unmarshaler))}
+	option := &options{
+		Config: Config{
+			delimiter: ".",
+		},
+	}
+	for _, opt := range opts {
+		opt(option)
+	}
+	option.values = &provider{values: make(map[string]any)}
+	option.providers = make([]*provider, 0, len(option.loaders))
+	option.onChanges = &onChanges{onChanges: make(map[string][]func(Unmarshaler))}
 
 	for _, loader := range option.loaders {
 		if loader == nil {
@@ -45,7 +51,7 @@ func New(opts ...Option) (Config, error) {
 		if err != nil {
 			return Config{}, fmt.Errorf("[konf] load configuration: %w", err)
 		}
-		maps.Merge(config.values.values, values)
+		maps.Merge(option.values.values, values)
 		slog.Info(
 			"Configuration has been loaded.",
 			"loader", loader,
@@ -57,10 +63,10 @@ func New(opts ...Option) (Config, error) {
 		if w, ok := loader.(Watcher); ok {
 			provider.watcher = w
 		}
-		config.providers = append(config.providers, provider)
+		option.providers = append(option.providers, provider)
 	}
 
-	return config, nil
+	return option.Config, nil
 }
 
 // Watch watches and updates configuration when it changes.
diff --git a/option.go b/option.go
index 11bd6461..2e3b8242 100644
--- a/option.go
+++ b/option.go
@@ -8,8 +8,8 @@ package konf
 // Each loader takes precedence over the loaders before it
 // while multiple loaders are specified.
 func WithLoader(loaders ...Loader) Option {
-	return func(config *options) {
-		config.loaders = append(config.loaders, loaders...)
+	return func(options *options) {
+		options.loaders = append(options.loaders, loaders...)
 	}
 }
 
@@ -17,8 +17,8 @@ func WithLoader(loaders ...Loader) Option {
 //
 // The default delimiter is `.`, which makes config path like `parent.child.key`.
 func WithDelimiter(delimiter string) Option {
-	return func(config *options) {
-		config.delimiter = delimiter
+	return func(options *options) {
+		options.delimiter = delimiter
 	}
 }
 
@@ -30,16 +30,3 @@ type options struct {
 
 	loaders []Loader
 }
-
-func apply(opts []Option) options {
-	option := &options{
-		Config: Config{
-			delimiter: ".",
-		},
-	}
-	for _, opt := range opts {
-		opt(option)
-	}
-
-	return *option
-}
diff --git a/provider/env/env.go b/provider/env/env.go
index 88d579b4..6220aa3a 100644
--- a/provider/env/env.go
+++ b/provider/env/env.go
@@ -29,7 +29,14 @@ type Env struct {
 
 // New returns an Env with the given Option(s).
 func New(opts ...Option) Env {
-	return Env(apply(opts))
+	option := &options{
+		delimiter: "_",
+	}
+	for _, opt := range opts {
+		opt(option)
+	}
+
+	return Env(*option)
 }
 
 func (e Env) Load() (map[string]any, error) {
diff --git a/provider/env/option.go b/provider/env/option.go
index 94549976..b838a990 100644
--- a/provider/env/option.go
+++ b/provider/env/option.go
@@ -8,8 +8,8 @@ package env
 // E.g. if the given prefix is "server", it only loads environment variables
 // which name starts with "server".
 func WithPrefix(prefix string) Option {
-	return func(env *options) {
-		env.prefix = prefix
+	return func(options *options) {
+		options.prefix = prefix
 	}
 }
 
@@ -18,8 +18,8 @@ func WithPrefix(prefix string) Option {
 // The default delimiter is `_`, which loads the environment variable `PARENT_CHILD_KEY="1"`
 // as `{PARENT: {CHILD: {KEY: "1"}}}`.
 func WithDelimiter(delimiter string) Option {
-	return func(env *options) {
-		env.delimiter = delimiter
+	return func(options *options) {
+		options.delimiter = delimiter
 	}
 }
 
@@ -27,14 +27,3 @@ func WithDelimiter(delimiter string) Option {
 type Option func(*options)
 
 type options Env
-
-func apply(opts []Option) options {
-	option := &options{
-		delimiter: "_",
-	}
-	for _, opt := range opts {
-		opt(option)
-	}
-
-	return *option
-}
diff --git a/provider/flag/flag.go b/provider/flag/flag.go
index 11f010c7..d0f0d691 100644
--- a/provider/flag/flag.go
+++ b/provider/flag/flag.go
@@ -33,13 +33,18 @@ type Flag struct {
 
 // New returns a Flag with the given Option(s).
 func New(opts ...Option) Flag {
-	option := apply(opts)
+	option := &options{
+		delimiter: ".",
+	}
+	for _, opt := range opts {
+		opt(option)
+	}
 	if option.set == nil {
 		flag.Parse()
 		option.set = flag.CommandLine
 	}
 
-	return Flag(option)
+	return Flag(*option)
 }
 
 func (f Flag) Load() (map[string]any, error) {
diff --git a/provider/flag/option.go b/provider/flag/option.go
index 0c200025..d0e506c1 100644
--- a/provider/flag/option.go
+++ b/provider/flag/option.go
@@ -10,8 +10,8 @@ import "flag"
 // E.g. if the given prefix is "server", it only loads flags
 // which name starts with "server".
 func WithPrefix(prefix string) Option {
-	return func(flag *options) {
-		flag.prefix = prefix
+	return func(options *options) {
+		options.prefix = prefix
 	}
 }
 
@@ -19,8 +19,8 @@ func WithPrefix(prefix string) Option {
 //
 // The default flag set is [flag.CommandLine].
 func WithFlagSet(set *flag.FlagSet) Option {
-	return func(flag *options) {
-		flag.set = set
+	return func(options *options) {
+		options.set = set
 	}
 }
 
@@ -29,8 +29,8 @@ func WithFlagSet(set *flag.FlagSet) Option {
 // The default delimiter is `_`, which loads the flag `parent.child.key` with value 1
 // as `{parent: {child: {key: 1}}}`.
 func WithDelimiter(delimiter string) Option {
-	return func(flag *options) {
-		flag.delimiter = delimiter
+	return func(options *options) {
+		options.delimiter = delimiter
 	}
 }
 
@@ -38,14 +38,3 @@ func WithDelimiter(delimiter string) Option {
 type Option func(*options)
 
 type options Flag
-
-func apply(opts []Option) options {
-	option := &options{
-		delimiter: ".",
-	}
-	for _, opt := range opts {
-		opt(option)
-	}
-
-	return *option
-}
diff --git a/provider/pflag/option.go b/provider/pflag/option.go
index 34dbdbe0..ad9237c7 100644
--- a/provider/pflag/option.go
+++ b/provider/pflag/option.go
@@ -10,8 +10,8 @@ import "github.com/spf13/pflag"
 // E.g. if the given prefix is "server", it only loads flags
 // which name starts with "server".
 func WithPrefix(prefix string) Option {
-	return func(pflag *options) {
-		pflag.prefix = prefix
+	return func(options *options) {
+		options.prefix = prefix
 	}
 }
 
@@ -19,8 +19,8 @@ func WithPrefix(prefix string) Option {
 //
 // The default flag set is [pflag.CommandLine] plus [flag.CommandLine].
 func WithFlagSet(set *pflag.FlagSet) Option {
-	return func(pflag *options) {
-		pflag.set = set
+	return func(options *options) {
+		options.set = set
 	}
 }
 
@@ -29,8 +29,8 @@ func WithFlagSet(set *pflag.FlagSet) Option {
 // The default delimiter is `_`, which loads the flag `parent.child.key` with value 1
 // as `{parent: {child: {key: 1}}}`.
 func WithDelimiter(delimiter string) Option {
-	return func(pflag *options) {
-		pflag.delimiter = delimiter
+	return func(options *options) {
+		options.delimiter = delimiter
 	}
 }
 
@@ -38,14 +38,3 @@ func WithDelimiter(delimiter string) Option {
 type Option func(*options)
 
 type options PFlag
-
-func apply(opts []Option) options {
-	option := &options{
-		delimiter: ".",
-	}
-	for _, opt := range opts {
-		opt(option)
-	}
-
-	return *option
-}
diff --git a/provider/pflag/pflag.go b/provider/pflag/pflag.go
index bb1b614f..f629c30b 100644
--- a/provider/pflag/pflag.go
+++ b/provider/pflag/pflag.go
@@ -35,14 +35,19 @@ type PFlag struct {
 
 // New returns a PFlag with the given Option(s).
 func New(opts ...Option) PFlag {
-	option := apply(opts)
+	option := &options{
+		delimiter: ".",
+	}
+	for _, opt := range opts {
+		opt(option)
+	}
 	if option.set == nil {
 		pflag.CommandLine.AddGoFlagSet(flag.CommandLine)
 		pflag.Parse()
 		option.set = pflag.CommandLine
 	}
 
-	return PFlag(option)
+	return PFlag(*option)
 }
 
 func (f PFlag) Load() (map[string]any, error) {