diff --git a/internal/ircserver/relay.go b/internal/ircserver/relay.go
index cb7d185..6d4195f 100644
--- a/internal/ircserver/relay.go
+++ b/internal/ircserver/relay.go
@@ -128,7 +128,11 @@ func (c *Conn) deliverIRCMessage(
 	default:
 		// Unknown command — deliver as server notice.
 		if text != "" {
-			c.sendFromServer("NOTICE", c.nick, text)
+			c.mu.Lock()
+			nick := c.nick
+			c.mu.Unlock()
+
+			c.sendFromServer("NOTICE", nick, text)
 		}
 	}
 }
@@ -158,8 +162,12 @@ func (c *Conn) deliverNumeric(
 		_ = json.Unmarshal(msg.Params, &params)
 	}
 
+	c.mu.Lock()
+	nick := c.nick
+	c.mu.Unlock()
+
 	allParams := make([]string, 0, 1+len(params)+1)
-	allParams = append(allParams, c.nick)
+	allParams = append(allParams, nick)
 	allParams = append(allParams, params...)
 
 	if text != "" {
@@ -177,8 +185,12 @@ func (c *Conn) deliverTextMessage(
 	from := msg.From
 	target := msg.To
 
+	c.mu.Lock()
+	nick := c.nick
+	c.mu.Unlock()
+
 	// Don't echo our own messages back.
-	if strings.EqualFold(from, c.nick) {
+	if strings.EqualFold(from, nick) {
 		return
 	}
 
@@ -192,9 +204,13 @@ func (c *Conn) deliverTextMessage(
 
 // deliverJoin sends a JOIN notification.
 func (c *Conn) deliverJoin(msg *db.IRCMessage) {
+	c.mu.Lock()
+	nick := c.nick
+	c.mu.Unlock()
+
 	// Don't echo our own JOINs (we already sent them
 	// during joinChannel).
-	if strings.EqualFold(msg.From, c.nick) {
+	if strings.EqualFold(msg.From, nick) {
 		return
 	}
 
@@ -206,7 +222,11 @@ func (c *Conn) deliverJoin(msg *db.IRCMessage) {
 
 // deliverPart sends a PART notification.
 func (c *Conn) deliverPart(msg *db.IRCMessage, text string) {
-	if strings.EqualFold(msg.From, c.nick) {
+	c.mu.Lock()
+	nick := c.nick
+	c.mu.Unlock()
+
+	if strings.EqualFold(msg.From, nick) {
 		return
 	}
 
@@ -227,7 +247,11 @@ func (c *Conn) deliverNickChange(
 	msg *db.IRCMessage,
 	newNick string,
 ) {
-	if strings.EqualFold(msg.From, c.nick) {
+	c.mu.Lock()
+	nick := c.nick
+	c.mu.Unlock()
+
+	if strings.EqualFold(msg.From, nick) {
 		return
 	}
 
@@ -241,7 +265,11 @@ func (c *Conn) deliverQuitMsg(
 	msg *db.IRCMessage,
 	text string,
 ) {
-	if strings.EqualFold(msg.From, c.nick) {
+	c.mu.Lock()
+	nick := c.nick
+	c.mu.Unlock()
+
+	if strings.EqualFold(msg.From, nick) {
 		return
 	}
 
@@ -302,7 +330,11 @@ func (c *Conn) deliverInviteMsg(
 	_ *db.IRCMessage,
 	text string,
 ) {
-	c.sendFromServer("NOTICE", c.nick, text)
+	c.mu.Lock()
+	nick := c.nick
+	c.mu.Unlock()
+
+	c.sendFromServer("NOTICE", nick, text)
 }
 
 // deliverMode sends a MODE change notification.