diff --git a/src/libcore/str/ascii.rs b/src/libcore/str/ascii.rs
index 9180c995ca2..73f556518fa 100644
--- a/src/libcore/str/ascii.rs
+++ b/src/libcore/str/ascii.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+//! Operations on ASCII strings and characters.
+
 use to_str::{ToStr,ToStrConsume};
 use str;
 use cast;