diff --git a/message.go b/message.go
index b219fcc..b591d9a 100644
--- a/message.go
+++ b/message.go
@@ -61,7 +61,7 @@ func (m *Message) Sender() (*User, error) {
 	if m.FromUserName == m.Bot.self.User.UserName {
 		return m.Bot.self.User, nil
 	}
-	user, err := members.SearchByUserName(m.FromUserName)
+	user, err := members.searchByUserNameLimit1(m.FromUserName)
 	if err != nil {
 		return nil, err
 	}
@@ -81,7 +81,7 @@ func (m *Message) SenderInGroup() (*User, error) {
 	if err != nil {
 		return nil, err
 	}
-	return group.MemberList.SearchByUserName(m.senderInGroupUserName)
+	return group.MemberList.searchByUserNameLimit1(m.senderInGroupUserName)
 }
 
 func (m *Message) Receiver() (*User, error) {
@@ -89,10 +89,10 @@ func (m *Message) Receiver() (*User, error) {
 		if sender, err := m.Sender(); err != nil {
 			return nil, err
 		} else {
-			return sender.MemberList.SearchByUserName(m.ToUserName)
+			return sender.MemberList.searchByUserNameLimit1(m.ToUserName)
 		}
 	} else {
-		return m.Bot.self.MemberList.SearchByUserName(m.ToUserName)
+		return m.Bot.self.MemberList.searchByUserNameLimit1(m.ToUserName)
 	}
 }
 
diff --git a/user.go b/user.go
index 0569eb6..ede7d40 100644
--- a/user.go
+++ b/user.go
@@ -162,7 +162,7 @@ func (s *Self) FileHelper() (*Friend, error) {
 	if err != nil {
 		return nil, err
 	}
-	user, err := members.SearchByUserName("filehelper")
+	user, err := members.searchByUserNameLimit1("filehelper")
 	if err != nil {
 		return nil, err
 	}
@@ -298,7 +298,7 @@ func (m Members) SetOwner(s *Self) {
 	}
 }
 
-func (m Members) SearchByUserName(username string) (*User, error) {
+func (m Members) searchByUserNameLimit1(username string) (*User, error) {
 	for _, member := range m {
 		if member.UserName == username {
 			return member, nil