diff --git a/pkg/captcha/captcha.go b/pkg/captcha/captcha.go
index f281723..5ca6f24 100644
--- a/pkg/captcha/captcha.go
+++ b/pkg/captcha/captcha.go
@@ -17,9 +17,14 @@ var DefaultConfig = base64Captcha.DriverString{
 	Source:          "1234567890qwertyuioplkjhgfdsazxcvbnm",
 	Fonts:           []string{"wqy-microhei.ttc", "chromohv.ttf", "actionj.ttf", "RitaSmith.ttf"},
 }
+var DefaultStore = base64Captcha.DefaultMemStore
 
-func Generate(store base64Captcha.Store) (id, b64s string, err error) {
-	return base64Captcha.NewCaptcha(&DefaultConfig, store).Generate()
+func SetStore(store base64Captcha.Store) {
+	DefaultStore = store
+}
+
+func Generate() (id, b64s string, err error) {
+	return base64Captcha.NewCaptcha(&DefaultConfig, DefaultStore).Generate()
 }
 
 type redisStore struct {
@@ -33,7 +38,7 @@ func NewRedisStore(redis *redis.Client) *redisStore {
 }
 
 func (r *redisStore) Key(key string) string {
-	return fmt.Sprintf("captach::%s", key)
+	return fmt.Sprintf("captach:%s", key)
 }
 func (r *redisStore) Set(id string, value string) error {
 	return r.redis.Set(r.Key(id), value, time.Second*3700).Err()