diff --git a/main.go b/main.go
index da40b56..d66586e 100644
--- a/main.go
+++ b/main.go
@@ -32,8 +32,8 @@ type Config struct {
 var (
 	config                = flag.String("config", "gocw2.cfg", "config file path")
 	history               = flag.Bool("history", false, "initialize chat history")
-	historyChatID64       = flag.int64("chat_id", nil, "chat to historize")
-	historySenderUserID64 = flag.int64("sender_user_id", nil, "sender_user_id to historize")
+	historyChatID64       = flag.Int64("chat_id", 0, "chat to historize")
+	historySenderUserID64 = flag.Int64("sender_user_id", 0, "sender_user_id to historize")
 
 	cfg Config
 
diff --git a/td.go b/td.go
index 999c91e..b114296 100644
--- a/td.go
+++ b/td.go
@@ -72,10 +72,10 @@ func getHistory(c *tdlib.Client, chatID64 int64, senderUserID64 int64) {
 	var msgCount int32 = 0
 	var lastMsgTime time.Time = time.Now()
 
-	if chatID64 == nil {
-		c := user_chtwrsbot
+	if chatID64 == 0 {
+		chat := user_chtwrsbot
 	} else {
-		c = chatID64
+		chat = chatID64
 	}
 
 	for lastMsgID64 >= 0 {