diff --git a/client/commands.go b/client/commands.go
index 20e3a66..164e04e 100644
--- a/client/commands.go
+++ b/client/commands.go
@@ -96,8 +96,14 @@ func (conn *Conn) User(ident, name string) {
 	conn.Raw(USER + " " + ident + " 12 * :" + name)
 }
 
-// Join() sends a JOIN command to the server
-func (conn *Conn) Join(channel string) { conn.Raw(JOIN + " " + channel) }
+// Join() sends a JOIN command to the server with an optional key
+func (conn *Conn) Join(channel string, key ...string) {
+	k := ""
+	if len(key) > 0 {
+		k = " " + key[0]
+	}
+	conn.Raw(JOIN + " " + channel + k)
+}
 
 // Part() sends a PART command to the server with an optional part message
 func (conn *Conn) Part(channel string, message ...string) {
diff --git a/client/commands_test.go b/client/commands_test.go
index dabaf61..a4d457e 100644
--- a/client/commands_test.go
+++ b/client/commands_test.go
@@ -97,6 +97,8 @@ func TestClientCommands(t *testing.T) {
 
 	c.Join("#foo")
 	s.nc.Expect("JOIN #foo")
+	c.Join("#foo bar")
+	s.nc.Expect("JOIN #foo bar")
 
 	c.Part("#foo")
 	s.nc.Expect("PART #foo")