diff --git a/README.md b/README.md
index aa0ed60..1712152 100644
--- a/README.md
+++ b/README.md
@@ -14,7 +14,7 @@ A portable RSA implementation in pure Rust.
 ```rust
 use rsa::{Pkcs1v15Encrypt, RsaPrivateKey, RsaPublicKey};
 
-let mut rng = rand::thread_rng();
+let mut rng = rand::thread_rng(); // rand@0.8
 let bits = 2048;
 let priv_key = RsaPrivateKey::new(&mut rng, bits).expect("failed to generate a key");
 let pub_key = RsaPublicKey::from(&priv_key);
diff --git a/src/lib.rs b/src/lib.rs
index f78b9eb..14d1a85 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -26,7 +26,7 @@
 #![cfg_attr(not(feature = "sha2"), doc = "```ignore")]
 //! use rsa::{RsaPrivateKey, RsaPublicKey, Oaep, sha2::Sha256};
 //!
-//! let mut rng = rand::thread_rng();
+//! let mut rng = rand::thread_rng(); // rand@0.8
 //!
 //! let bits = 2048;
 //! let private_key = RsaPrivateKey::new(&mut rng, bits).expect("failed to generate a key");
@@ -48,7 +48,7 @@
 //! ```
 //! use rsa::{RsaPrivateKey, RsaPublicKey, Pkcs1v15Encrypt};
 //!
-//! let mut rng = rand::thread_rng();
+//! let mut rng = rand::thread_rng(); // rand@0.8
 //!
 //! let bits = 2048;
 //! let private_key = RsaPrivateKey::new(&mut rng, bits).expect("failed to generate a key");
@@ -75,7 +75,7 @@
 //! use rsa::signature::{Keypair, RandomizedSigner, SignatureEncoding, Verifier};
 //! use rsa::sha2::{Digest, Sha256};
 //!
-//! let mut rng = rand::thread_rng();
+//! let mut rng = rand::thread_rng(); // rand@0.8
 //!
 //! let bits = 2048;
 //! let private_key = RsaPrivateKey::new(&mut rng, bits).expect("failed to generate a key");
@@ -102,7 +102,7 @@
 //! use rsa::signature::{Keypair,RandomizedSigner, SignatureEncoding, Verifier};
 //! use rsa::sha2::{Digest, Sha256};
 //!
-//! let mut rng = rand::thread_rng();
+//! let mut rng = rand::thread_rng(); // rand@0.8
 //!
 //! let bits = 2048;
 //! let private_key = RsaPrivateKey::new(&mut rng, bits).expect("failed to generate a key");
diff --git a/src/oaep.rs b/src/oaep.rs
index 13ac8d7..a8bcbd1 100644
--- a/src/oaep.rs
+++ b/src/oaep.rs
@@ -62,7 +62,7 @@ impl Oaep {
     /// let n = BoxedUint::from_be_slice(&n_bytes, 2048).unwrap();
     /// let e = BoxedUint::from_be_slice(&e_bytes, 32).unwrap();
     ///
-    /// let mut rng = rand::thread_rng();
+    /// let mut rng = rand::thread_rng(); // rand@0.8
     /// let key = RsaPublicKey::new(n, e).unwrap();
     /// let padding = Oaep::new::<Sha256>();
     /// let encrypted_data = key.encrypt(&mut rng, padding, b"secret").unwrap();
@@ -102,7 +102,7 @@ impl Oaep {
     /// let n = BoxedUint::from_be_slice(&n_bytes, 2048).unwrap();
     /// let e = BoxedUint::from_be_slice(&e_bytes, 32).unwrap();
     ///
-    /// let mut rng = rand::thread_rng();
+    /// let mut rng = rand::thread_rng(); // rand@0.8
     /// let key = RsaPublicKey::new(n, e).unwrap();
     /// let padding = Oaep::new_with_mgf_hash::<Sha256, Sha1>();
     /// let encrypted_data = key.encrypt(&mut rng, padding, b"secret").unwrap();