diff --git a/Cargo.toml b/Cargo.toml
index 8298c07..7dc63a7 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -19,10 +19,15 @@ travis-ci = { repository = "dalek-cryptography/ed25519-dalek", branch = "master"
 version = "1"
 default-features = false
 
+[dependencies.rand_core]
+version = "0.3"
+default-features = false
+
 [dependencies.rand]
 version = "0.6"
 features = ["i128_support"]
 default-features = false
+optional = true
 
 [dependencies.serde]
 version = "^1.0"
@@ -43,6 +48,8 @@ version = "0.2"
 hex = "^0.3"
 bincode = "^0.9"
 criterion = "0.2"
+rand_os = "0.1.0"
+rand_chacha = "0.1.0"
 
 [[bench]]
 name = "ed25519_benchmarks"
@@ -50,9 +57,9 @@ harness = false
 
 [features]
 default = ["std", "u64_backend"]
-std = ["curve25519-dalek/std", "rand/std", "sha2/std"]
+std = ["curve25519-dalek/std", "rand", "sha2/std"]
 alloc = ["curve25519-dalek/alloc"]
-nightly = ["curve25519-dalek/nightly", "rand/nightly", "clear_on_drop/nightly"]
+nightly = ["curve25519-dalek/nightly", "clear_on_drop/nightly"]
 asm = ["sha2/asm"]
 yolocrypto = ["curve25519-dalek/yolocrypto"]
 u64_backend = ["curve25519-dalek/u64_backend"]
diff --git a/src/ed25519.rs b/src/ed25519.rs
index 7262bee..f483bd1 100644
--- a/src/ed25519.rs
+++ b/src/ed25519.rs
@@ -12,8 +12,7 @@
 #[allow(unused_imports)]
 use core::default::Default;
 
-use rand::CryptoRng;
-use rand::Rng;
+use rand_core::{CryptoRng, RngCore};
 
 #[cfg(feature = "serde")]
 use serde::de::Error as SerdeError;
@@ -49,8 +48,7 @@ pub use crate::signature::*;
 /// * `messages` is a slice of byte slices, one per signed message.
 /// * `signatures` is a slice of `Signature`s.
 /// * `public_keys` is a slice of `PublicKey`s.
-/// * `csprng` is an implementation of `Rng + CryptoRng`, such as
-///   `rand::rngs::ThreadRng`.
+/// * `csprng` is an implementation of `Rng + CryptoRng`, such as `rand::rngs::ThreadRng`.
 ///
 /// # Panics
 ///
@@ -107,7 +105,7 @@ pub fn verify_batch(
     use std::vec::Vec;
 
     use core::iter::once;
-    use rand::thread_rng;
+    use rand::{Rng, thread_rng};
 
     use curve25519_dalek::traits::IsIdentity;
     use curve25519_dalek::traits::VartimeMultiscalarMul;
@@ -219,14 +217,13 @@ impl Keypair {
     /// # Example
     ///
     /// ```
-    /// extern crate rand;
+    /// extern crate rand_os;
     /// extern crate ed25519_dalek;
     ///
     /// # #[cfg(feature = "std")]
     /// # fn main() {
     ///
-    /// use rand::Rng;
-    /// use rand::rngs::OsRng;
+    /// use rand_os::OsRng;
     /// use ed25519_dalek::Keypair;
     /// use ed25519_dalek::Signature;
     ///
@@ -250,7 +247,7 @@ impl Keypair {
     /// Other suitable hash functions include Keccak-512 and Blake2b-512.
     pub fn generate<R>(csprng: &mut R) -> Keypair
     where
-        R: CryptoRng + Rng,
+        R: CryptoRng + RngCore,
     {
         let sk: SecretKey = SecretKey::generate(csprng);
         let pk: PublicKey = (&sk).into();
@@ -417,7 +414,7 @@ impl Keypair {
     /// let keypair: Keypair = Keypair::generate(&mut csprng);
     /// let message: &[u8] = b"All I want is to pet all of the dogs.";
     ///
-    /// let mut prehashed: Sha512 = Sha512::default();
+    /// let mut prehashed: Sha512 = Sha512::new();
     /// prehashed.input(message);
     ///
     /// let context: &[u8] = b"Ed25519DalekSignPrehashedDoctest";
diff --git a/src/lib.rs b/src/lib.rs
index faf6873..9b72ac8 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -19,13 +19,13 @@
 //! the operating system's builtin PRNG:
 //!
 //! ```
-//! extern crate rand;
+//! extern crate rand_os;
 //! extern crate ed25519_dalek;
 //!
 //! # #[cfg(feature = "std")]
 //! # fn main() {
 //! use rand::Rng;
-//! use rand::rngs::OsRng;
+//! use rand_os::OsRng;
 //! use ed25519_dalek::Keypair;
 //! use ed25519_dalek::Signature;
 //!
@@ -250,7 +250,11 @@ extern crate std;
 extern crate clear_on_drop;
 extern crate curve25519_dalek;
 extern crate failure;
+#[cfg(any(feature = "std", test))]
 extern crate rand;
+#[cfg(test)]
+extern crate rand_chacha;
+extern crate rand_core;
 #[cfg(feature = "serde")]
 extern crate serde;
 extern crate sha2;
diff --git a/src/secret.rs b/src/secret.rs
index 3bfeb7c..3e1a5d8 100644
--- a/src/secret.rs
+++ b/src/secret.rs
@@ -19,8 +19,7 @@ use curve25519_dalek::digest::Digest;
 use curve25519_dalek::edwards::CompressedEdwardsY;
 use curve25519_dalek::scalar::Scalar;
 
-use rand::CryptoRng;
-use rand::Rng;
+use rand_core::{CryptoRng, RngCore};
 
 use sha2::Sha512;
 
@@ -126,15 +125,14 @@ impl SecretKey {
     /// # Example
     ///
     /// ```
-    /// extern crate rand;
+    /// extern crate rand_os;
     /// extern crate sha2;
     /// extern crate ed25519_dalek;
     ///
     /// # #[cfg(feature = "std")]
     /// # fn main() {
     /// #
-    /// use rand::Rng;
-    /// use rand::rngs::OsRng;
+    /// use rand_os::OsRng;
     /// use sha2::Sha512;
     /// use ed25519_dalek::PublicKey;
     /// use ed25519_dalek::SecretKey;
@@ -323,15 +321,14 @@ impl ExpandedSecretKey {
     /// # Examples
     ///
     /// ```
-    /// # extern crate rand;
+    /// # extern crate rand_os;
     /// # extern crate sha2;
     /// # extern crate ed25519_dalek;
     /// #
     /// # #[cfg(all(feature = "sha2", feature = "std"))]
     /// # fn main() {
     /// #
-    /// use rand::Rng;
-    /// use rand::rngs::OsRng;
+    /// use rand_os::OsRng;
     /// use sha2::Sha512;
     /// use ed25519_dalek::{SecretKey, ExpandedSecretKey};
     ///
@@ -365,7 +362,7 @@ impl ExpandedSecretKey {
     /// # Examples
     ///
     /// ```
-    /// # extern crate rand;
+    /// # extern crate rand_os;
     /// # extern crate sha2;
     /// # extern crate ed25519_dalek;
     /// #
@@ -374,8 +371,7 @@ impl ExpandedSecretKey {
     /// # #[cfg(all(feature = "sha2", feature = "std"))]
     /// # fn do_test() -> Result<ExpandedSecretKey, SignatureError> {
     /// #
-    /// use rand::Rng;
-    /// use rand::rngs::OsRng;
+    /// use rand_os::OsRng;
     /// use ed25519_dalek::{SecretKey, ExpandedSecretKey};
     /// use ed25519_dalek::SignatureError;
     ///