diff --git a/doc/index.md b/doc/index.md
index 6b9c1ca..39a3771 100644
--- a/doc/index.md
+++ b/doc/index.md
@@ -17,4 +17,4 @@
 
 * Server Replies, documented
    * Errors
-      * [421 - Not Found](notfound.md)
\ No newline at end of file
+      * [421 - Unknown command](notfound.md)
\ No newline at end of file