diff --git a/model/user.go b/model/user.go
index 9bea5aa3..17452159 100644
--- a/model/user.go
+++ b/model/user.go
@@ -22,7 +22,7 @@ type User struct {
 	Likings         []User    `gorm:"foreignkey:userId;associationforeignkey:follower_id;many2many:user_follows"`
 	Liked           []User    `gorm:"foreignkey:follower_id;associationforeignkey:userId;many2many:user_follows"`
 
-	Md5             string     `json:"md5"`
+	Md5             string     `json:"md5"` // Used for gravatar
 	Torrents        []Torrents `gorm:"ForeignKey:UploaderId"`
 }
 
diff --git a/service/user/user.go b/service/user/user.go
index b01ef6a5..32e55e89 100644
--- a/service/user/user.go
+++ b/service/user/user.go
@@ -61,17 +61,25 @@ func CreateUserFromForm(registrationForm formStruct.RegistrationForm) (model.Use
 	var user model.User
 	log.Debugf("registrationForm %+v\n", registrationForm)
 	modelHelper.AssignValue(&user, &registrationForm)
-	user.Md5 = crypto.GenerateMD5Hash(user.Email)  // Gravatar
+
+	if user.Email == "" {
+		user.Md5 = ""
+	} else {
+		user.Md5 = crypto.GenerateMD5Hash(user.Email)
+	}
 	token, err := crypto.GenerateRandomToken32()
 	if err != nil {
 		return user, errors.New("Token not generated.")
 	}
+
 	user.Token = token
 	user.TokenExpiration = timeHelper.FewDaysLater(config.AuthTokenExpirationDay)
 	log.Debugf("user %+v\n", user)
 	if db.ORM.Create(&user).Error != nil {
 		return user, errors.New("User is not created.")
 	}
+
+	user.CreatedAt = time.Now()
 	return user, nil
 }
 
@@ -136,7 +144,12 @@ func RetrieveUsers() []*model.PublicUser {
 
 // UpdateUserCore updates a user. (Applying the modifed data of user).
 func UpdateUserCore(user *model.User) (int, error) {
-	user.Md5 = crypto.GenerateMD5Hash(user.Email)
+	if user.Email == "" {
+		user.Md5 = ""
+	} else {
+		user.Md5 = crypto.GenerateMD5Hash(user.Email)
+	}
+
 	token, err := crypto.GenerateRandomToken32()
 	if err != nil {
 		return http.StatusInternalServerError, errors.New("Token not generated.")
@@ -146,6 +159,7 @@ func UpdateUserCore(user *model.User) (int, error) {
 	if db.ORM.Save(user).Error != nil {
 		return http.StatusInternalServerError, errors.New("User is not updated.")
 	}
+
 	user.UpdatedAt = time.Now()
 	return http.StatusOK, nil
 }