diff --git a/core/core_test.go b/core/core_test.go
index f251c78..0953562 100644
--- a/core/core_test.go
+++ b/core/core_test.go
@@ -226,7 +226,7 @@ func TestCore_Decode_ErrUnsupporetedType(t *testing.T) {
 		co, err := New(Cursor{})
 		assert.NoError(t, err)
 		got, err := co.Decode(r)
-		assert.ErrorIs(t, err, internal.ErrUnsupportedType)
+		assert.ErrorIs(t, err, owl.ErrUnsupportedType)
 		assert.ErrorContains(t, err, "ObjectID")
 		assert.Nil(t, got)
 	}()
@@ -244,7 +244,7 @@ func TestCore_Decode_ErrUnsupporetedType(t *testing.T) {
 		co, err := New(Payload{})
 		assert.NoError(t, err)
 		got, err := co.Decode(r)
-		assert.ErrorIs(t, err, internal.ErrUnsupportedType)
+		assert.ErrorIs(t, err, owl.ErrUnsupportedType)
 		assert.ErrorContains(t, err, "ObjectID")
 		assert.Nil(t, got)
 	}()
diff --git a/core/query_test.go b/core/query_test.go
index 65c1f45..dc37c8a 100644
--- a/core/query_test.go
+++ b/core/query_test.go
@@ -6,8 +6,8 @@ import (
 	"net/url"
 	"testing"
 
-	"github.com/ggicci/httpin/internal"
 	"github.com/stretchr/testify/assert"
+	"github.com/ggicci/owl"
 )
 
 func TestDirectiveQuery_Decode(t *testing.T) {
@@ -106,7 +106,7 @@ func TestDirectiveQuery_NewRequest_ErrUnsupportedType(t *testing.T) {
 	co, err := New(SearchQuery{})
 	assert.NoError(t, err)
 	_, err = co.NewRequest("GET", "/pets", &SearchQuery{})
-	assert.ErrorIs(t, err, internal.ErrUnsupportedType)
+	assert.ErrorIs(t, err, owl.ErrUnsupportedType)
 }
 
 // See hybridcoder_test.go for more details.
diff --git a/core/stringable_test.go b/core/stringable_test.go
index 48f4b4f..27a906e 100644
--- a/core/stringable_test.go
+++ b/core/stringable_test.go
@@ -9,6 +9,7 @@ import (
 	"github.com/ggicci/httpin/internal"
 	"github.com/ggicci/httpin/patch"
 	"github.com/stretchr/testify/assert"
+	"github.com/ggicci/owl"
 )
 
 type Point2D struct {
@@ -234,7 +235,7 @@ func testAssignString(t *testing.T, rv reflect.Value, value string) {
 
 func testNewStringableErrUnsupported(t *testing.T, rv reflect.Value) {
 	s, err := NewStringable(rv, nil)
-	assert.ErrorIs(t, err, internal.ErrUnsupportedType)
+	assert.ErrorIs(t, err, owl.ErrUnsupportedType)
 	assert.Nil(t, s)
 }
 
diff --git a/internal/stringable.go b/internal/stringable.go
index 852549d..1300cda 100644
--- a/internal/stringable.go
+++ b/internal/stringable.go
@@ -9,11 +9,11 @@ import (
 	"strconv"
 	"strings"
 	"time"
+	"github.com/ggicci/owl"
 )
 
 var (
-	ErrUnsupportedType = errors.New("unsupported type")
-	ErrTypeMismatch    = errors.New("type mismatch")
+	ErrTypeMismatch = errors.New("type mismatch")
 
 	builtinStringableAdaptors = make(map[reflect.Type]AnyStringableAdaptor)
 )
@@ -380,5 +380,5 @@ func (bs *ByteSlice) FromString(s string) error {
 }
 
 func UnsupportedType(rt reflect.Type) error {
-	return fmt.Errorf("%w: %v", ErrUnsupportedType, rt)
+	return fmt.Errorf("%w: %v", owl.ErrUnsupportedType, rt)
 }
diff --git a/internal/stringable_test.go b/internal/stringable_test.go
index ac4ebf6..8072fa8 100644
--- a/internal/stringable_test.go
+++ b/internal/stringable_test.go
@@ -7,6 +7,7 @@ import (
 	"time"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/ggicci/owl"
 )
 
 func TestNewStringable_string(t *testing.T) {
@@ -156,7 +157,7 @@ func TestNewStringable_ErrUnsupportedType(t *testing.T) {
 	})
 	rvStructPointer := reflect.ValueOf(&s)
 	sv, err := NewStringable(rvStructPointer)
-	assert.ErrorIs(t, err, ErrUnsupportedType)
+	assert.ErrorIs(t, err, owl.ErrUnsupportedType)
 	assert.Nil(t, sv)
 }