diff --git a/openssl/src/bn.rs b/openssl/src/bn.rs
index 46d7d8f3..9b342a28 100644
--- a/openssl/src/bn.rs
+++ b/openssl/src/bn.rs
@@ -1,3 +1,6 @@
+//! BigNum implementation
+//!
+//! 
 use ffi;
 use foreign_types::{ForeignType, ForeignTypeRef};
 use libc::c_int;