diff --git a/crates/ra_proc_macro_srv/src/main.rs b/crates/ra_proc_macro_srv/src/main.rs
index 54ce0224db..70743c1f40 100644
--- a/crates/ra_proc_macro_srv/src/main.rs
+++ b/crates/ra_proc_macro_srv/src/main.rs
@@ -1,3 +1,5 @@
+//! Driver for proc macro server
+
 use ra_proc_macro::msg::{self, Message};
 use ra_proc_macro_srv::{expand_task, list_macros};