diff --git a/internal/captcha/captcha.go b/internal/captcha/captcha.go
index 31e3b2a..7e9387f 100644
--- a/internal/captcha/captcha.go
+++ b/internal/captcha/captcha.go
@@ -19,7 +19,7 @@ type ID string
 type Answer string
 
 type ICaptcha interface {
-	GenerateImage() *image.Image
+	generateImage() *image.Image
 	GetImage() *image.Image
 	GetAnswer() Answer
 	Solve(answer Answer) bool