diff --git a/core/mapping/unmarshaler.go b/core/mapping/unmarshaler.go
index 56e58839278d..a633453a1990 100644
--- a/core/mapping/unmarshaler.go
+++ b/core/mapping/unmarshaler.go
@@ -496,17 +496,20 @@ func (u *Unmarshaler) fillSlice(fieldType reflect.Type, value reflect.Value, map
 	return nil
 }
 
-func (u *Unmarshaler) fillSliceFromString(fieldType reflect.Type, value reflect.Value, mapValue interface{}) error {
+func (u *Unmarshaler) fillSliceFromString(fieldType reflect.Type, value reflect.Value,
+	mapValue interface{}) error {
 	var slice []interface{}
 	switch v := mapValue.(type) {
-	case json.Number:
+	case fmt.Stringer:
 		if err := jsonx.UnmarshalFromString(v.String(), &slice); err != nil {
 			return err
 		}
-	default:
-		if err := jsonx.UnmarshalFromString(mapValue.(string), &slice); err != nil {
+	case string:
+		if err := jsonx.UnmarshalFromString(v, &slice); err != nil {
 			return err
 		}
+	default:
+		return errUnsupportedType
 	}
 
 	baseFieldType := Deref(fieldType.Elem())
diff --git a/core/mapping/unmarshaler_test.go b/core/mapping/unmarshaler_test.go
index f3b037f0ea9f..da0424901ffe 100644
--- a/core/mapping/unmarshaler_test.go
+++ b/core/mapping/unmarshaler_test.go
@@ -2777,6 +2777,36 @@ func TestUnmarshalJsonReaderComplex(t *testing.T) {
 	assert.Equal(t, "txt", req.Txt)
 }
 
+func TestUnmarshalJsonReaderArrayBool(t *testing.T) {
+	payload := `{"id": false}`
+	var res struct {
+		ID []string `json:"id"`
+	}
+	reader := strings.NewReader(payload)
+	err := UnmarshalJsonReader(reader, &res)
+	assert.NotNil(t, err)
+}
+
+func TestUnmarshalJsonReaderArrayInt(t *testing.T) {
+	payload := `{"id": 123}`
+	var res struct {
+		ID []string `json:"id"`
+	}
+	reader := strings.NewReader(payload)
+	err := UnmarshalJsonReader(reader, &res)
+	assert.NotNil(t, err)
+}
+
+func TestUnmarshalJsonReaderArrayString(t *testing.T) {
+	payload := `{"id": "123"}`
+	var res struct {
+		ID []string `json:"id"`
+	}
+	reader := strings.NewReader(payload)
+	err := UnmarshalJsonReader(reader, &res)
+	assert.NotNil(t, err)
+}
+
 func BenchmarkDefaultValue(b *testing.B) {
 	for i := 0; i < b.N; i++ {
 		var a struct {
@@ -2789,14 +2819,3 @@ func BenchmarkDefaultValue(b *testing.B) {
 		}
 	}
 }
-
-func TestUnmarshalJsonReaderArray(t *testing.T) {
-	payload := "{\"id\": 123}"
-	var res struct {
-		ID []string   `json:"id"`
-	}
-	reader := strings.NewReader(payload)
-	err := UnmarshalJsonReader(reader, &res)
-	assert.Nil(t, err)
-	assert.Equal(t, 1, len(res.ID))
-}