diff --git a/pkg/captcha/inmemdb/inmemdb.go b/pkg/captcha/inmemdb/inmemdb.go
index 445499b..1fd697c 100644
--- a/pkg/captcha/inmemdb/inmemdb.go
+++ b/pkg/captcha/inmemdb/inmemdb.go
@@ -54,6 +54,7 @@ func (imcdb *InMemoryCaptchaDB) GetExpiry() time.Duration {
 
 // SetExpiry changes an expiry duration to a new one.
 func (imcdb *InMemoryCaptchaDB) SetExpiry(expiry time.Duration) {
+	imcdb.expiry = expiry
 	if expiry < captcha.DefaultExpiredScanInterval {
 		imcdb.expiryScanInterval = expiry
 	} else {