diff --git a/README.md b/README.md
index 34acdee..fe48ce6 100644
--- a/README.md
+++ b/README.md
@@ -21,7 +21,6 @@
 - [ ] IRCv3 spec -- [details](http://ircv3.net):
   - [ ] [account-notify](http://ircv3.net/specs/extensions/account-notify-3.1.html)
   - [ ] [account-tag](http://ircv3.net/specs/extensions/account-tag-3.2.html)
-  - [ ] [message-tags](http://ircv3.net/specs/core/message-tags-3.3.html)
   - [ ] [multi-prefix](http://ircv3.net/specs/extensions/multi-prefix-3.1.html)
   - [ ] [sasl](http://ircv3.net/specs/extensions/sasl-3.2.html)
   - [ ] [userhost-in-names](http://ircv3.net/specs/extensions/userhost-in-names-3.2.html)
diff --git a/tags.go b/tags.go
index 8600c6b..268054f 100644
--- a/tags.go
+++ b/tags.go
@@ -109,6 +109,8 @@ func (t Tags) String() string {
 	return string(t.Bytes())
 }
 
+// writeTo writes the necessary tag bytes to an io.Writer, including a trailing
+// space-separator.
 func (t Tags) writeTo(w io.Writer) (n int, err error) {
 	b := t.Bytes()
 	if len(b) == 0 {
@@ -186,6 +188,7 @@ func (t Tags) Remove(key string) (success bool) {
 	return success
 }
 
+// validTag validates an IRC tag.
 func validTag(name string) bool {
 	if len(name) < 1 {
 		return false