diff --git a/src/response.rs b/src/response.rs
index 61e54c9c..5c39f0d6 100644
--- a/src/response.rs
+++ b/src/response.rs
@@ -5,10 +5,13 @@ pub type Response = Result<(), MpdError>;
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
 pub enum ErrorCode {
+    // NOTE: seemingly unused
     NotList = 1,
     Arg = 2,
+    // NOTE: only used for 'password' command
     Password = 3,
     Permission = 4,
+    // NOTE: Catchall error
     Unknown = 5,
 
     NoExist = 50,