diff --git a/crates/projection-irc/tests/lib.rs b/crates/projection-irc/tests/lib.rs
index 240a067..36b9040 100644
--- a/crates/projection-irc/tests/lib.rs
+++ b/crates/projection-irc/tests/lib.rs
@@ -271,11 +271,10 @@ async fn scenario_two_users() -> Result<()> {
     // The first user should receive the message
     s1.expect(":tester2 PRIVMSG #test :Hello").await?;
     // Leave the channel from the first user
-    // TODO implement irc PART command
-    // s1.send("PART #test").await?;
-    // s1.expect(":tester1 PART #test").await?;
+    s1.send("PART #test").await?;
+    s1.expect(":tester1 PART #test").await?;
     // The second user should receive the PART message
-    // s2.expect(":tester1 PART #test").await?;
+    s2.expect(":tester1 PART #test").await?;
     Ok(())
 }
 
diff --git a/crates/proto-irc/src/client.rs b/crates/proto-irc/src/client.rs
index 66cf107..a692e92 100644
--- a/crates/proto-irc/src/client.rs
+++ b/crates/proto-irc/src/client.rs
@@ -49,7 +49,7 @@ pub enum ClientMessage {
     },
     Part {
         chan: Chan,
-        message: Str,
+        message: Option<Str>,
     },
     /// `PRIVMSG <target> :<msg>`
     PrivateMessage {
@@ -194,14 +194,20 @@ fn client_message_topic(input: &str) -> IResult<&str, ClientMessage> {
 fn client_message_part(input: &str) -> IResult<&str, ClientMessage> {
     let (input, _) = tag("PART ")(input)?;
     let (input, chan) = chan(input)?;
-    let (input, _) = tag(" ")(input)?;
+    let (input, t) = opt(tag(" "))(input)?;
+    match t {
+        Some(_) => (),
+        None => {
+            return Ok((input, ClientMessage::Part { chan, message: None }));
+        }
+    }
     let (input, r) = opt(tag(":"))(input)?;
     let (input, message) = match r {
         Some(_) => token(input)?,
         None => receiver(input)?,
     };
 
-    let message = message.into();
+    let message = Some(message.into());
     Ok((input, ClientMessage::Part { chan, message }))
 }
 
@@ -369,7 +375,18 @@ mod test {
         let input = "PART #chan :Pokasiki !!!";
         let expected = ClientMessage::Part {
             chan: Chan::Global("chan".into()),
-            message: "Pokasiki !!!".into(),
+            message: Some("Pokasiki !!!".into()),
+        };
+
+        let result = client_message(input);
+        assert_matches!(result, Ok(result) => assert_eq!(expected, result));
+    }
+    #[test]
+    fn test_client_message_part_empty() {
+        let input = "PART #chan";
+        let expected = ClientMessage::Part {
+            chan: Chan::Global("chan".into()),
+            message: None,
         };
 
         let result = client_message(input);