diff --git a/openapi/generator_test.go b/openapi/generator_test.go
index 072577f..314ddd3 100644
--- a/openapi/generator_test.go
+++ b/openapi/generator_test.go
@@ -741,12 +741,10 @@ func (c customUnit) ParseExample(v string) (interface{}, error) {
 	return fmt.Sprintf("%s USD", v), nil
 }
 
-type customTime struct {
-	time.Time
-}
+type customTime time.Time
 
 func (c customTime) String() string {
-	return c.Format("2006-01-02T15:04:05")
+	return time.Time(c).Format("2006-01-02T15:04:05")
 }
 
 func (c customTime) ParseExample(v string) (interface{}, error) {
@@ -754,7 +752,7 @@ func (c customTime) ParseExample(v string) (interface{}, error) {
 	if err != nil {
 		return nil, err
 	}
-	return customTime{t1}, nil
+	return customTime(t1), nil
 }
 
 // TestGenerator_parseExampleValue tests the parsing of example values.
@@ -913,13 +911,13 @@ func TestGenerator_parseExampleValue(t *testing.T) {
 			"mapping to customTime",
 			reflect.TypeOf(customTime{}),
 			"2022-02-07T18:00:00+09:00",
-			customTime{time.Date(2022, time.February, 7, 18, 0, 0, 0, time.FixedZone("", 9*3600))},
+			customTime(time.Date(2022, time.February, 7, 18, 0, 0, 0, time.FixedZone("", 9*3600))),
 		},
 		{
 			"mapping pointer to customTime",
 			reflect.PtrTo(reflect.TypeOf(customTime{})),
 			"2022-02-07T18:00:00+09:00",
-			customTime{time.Date(2022, time.February, 7, 18, 0, 0, 0, time.FixedZone("", 9*3600))},
+			customTime(time.Date(2022, time.February, 7, 18, 0, 0, 0, time.FixedZone("", 9*3600))),
 		},
 	}