diff --git a/internal/captcha/instance.go b/internal/captcha/instance.go
index 1440647..b695b52 100644
--- a/internal/captcha/instance.go
+++ b/internal/captcha/instance.go
@@ -6,15 +6,15 @@ import (
 	"time"
 )
 
-var captchaDb captcha.InMemoryCaptchaDB = captcha.InMemoryCaptchaDB{
-	DB: make(map[captcha.ID]captcha.Captcha)}
+var captchaDb captcha.CaptchaDB
 
 func Init(expiry time.Duration) {
-	captchaDb.SetExpiry(expiry)
+	captchaDb = captcha.NewInMemoryCaptchaDB(expiry)
 }
 
-func New(data string, captcha captcha.Captcha) (captcha.Captcha, captcha.ID) {
-	return captchaDb.New(data, captcha)
+func New(data string) (captcha.Captcha, captcha.ID) {
+	dc := NewDwellingCaptcha(captchaDb.GetExpiry())
+	return captchaDb.New(data, dc)
 }
 
 func Image(id captcha.ID, style string) (*image.Image, error) {