diff --git a/internal/captcha/instance.go b/internal/captcha/instance.go
index 238f75a..fea0322 100644
--- a/internal/captcha/instance.go
+++ b/internal/captcha/instance.go
@@ -6,18 +6,18 @@ import (
 	"time"
 )
 
-var captchaDb captcha.CaptchaDB = captcha.CaptchaDB{
-	DB: make(map[captcha.ID]captcha.ICaptcha)}
+var captchaDb captcha.InMemoryCaptchaDB = captcha.InMemoryCaptchaDB{
+	DB: make(map[captcha.ID]captcha.Captcha)}
 
 func Init(expiry time.Duration) {
 	captchaDb.SetExpiry(expiry)
 }
 
-func New(data string, captcha captcha.ICaptcha) (captcha.ICaptcha, captcha.ID) {
+func New(data string, captcha captcha.Captcha) (captcha.Captcha, captcha.ID) {
 	return captchaDb.New(data, captcha)
 }
 
-func Image(id captcha.ID, style string) (*image.Image, error) {
+func Image(id captcha.ID, style string) (image.Image, error) {
 	return captchaDb.Image(id, style)
 }