diff --git a/Cargo.toml b/Cargo.toml
index 7baed61..70381e6 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -12,18 +12,23 @@ license = "MIT OR Apache-2.0"
 edition = "2018"
 
 [dependencies]
-blake2b_simd = "0.5"
-byteorder = "1"
-chacha20 = "0.8"
-chacha20poly1305 = "0.9"
-ff = "0.11"
-group = "0.11"
-rand_core = "0.6"
-subtle = "2.2.3"
+blake2b_simd = { version = "0.5", default-features = false }
+byteorder = { version = "1", default-features = false }
+chacha20 = { version = "0.8", default-features = false }
+chacha20poly1305 = { version = "0.9", default-features = false }
+ff = { version = "0.11", default-features = false }
+group = { version = "0.11", default-features = false }
+rand_core = { version = "0.6", default-features = false }
+subtle = { version = "2.2.3", default-features = false }
 
 [dev-dependencies]
 zcash_primitives = { version = "0.5", path = "../../zcash_primitives" }
 jubjub = "0.8"
 
+[features]
+default = ["std"]
+alloc = []
+std = ["alloc", "blake2b_simd/std"]
+
 [lib]
 bench = false
diff --git a/src/batch.rs b/src/batch.rs
index cb5719a..93f2634 100644
--- a/src/batch.rs
+++ b/src/batch.rs
@@ -1,6 +1,7 @@
 //! APIs for batch trial decryption.
 
-use std::iter;
+use alloc::vec::Vec; // module is alloc only
+use core::iter;
 
 use crate::{
     try_compact_note_decryption_inner, try_note_decryption_inner, BatchDomain, EphemeralKeyBytes,
diff --git a/src/lib.rs b/src/lib.rs
index fcbaee7..9d4f03c 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -3,12 +3,18 @@
 //! functionality that is shared between the Sapling and Orchard
 //! protocols.
 
+#![no_std]
 // Catch documentation errors caused by code changes.
 #![deny(broken_intra_doc_links)]
 #![deny(unsafe_code)]
 // TODO: #![deny(missing_docs)]
 
-use std::convert::TryInto;
+#[cfg(feature = "alloc")]
+extern crate alloc;
+#[cfg(feature = "alloc")]
+use alloc::vec::Vec;
+
+use core::convert::TryInto;
 
 use chacha20::{
     cipher::{NewCipher, StreamCipher, StreamCipherSeek},
@@ -22,6 +28,7 @@ use chacha20poly1305::{
 use rand_core::RngCore;
 use subtle::{Choice, ConstantTimeEq};
 
+#[cfg(feature = "alloc")]
 pub mod batch;
 
 pub const COMPACT_NOTE_SIZE: usize = 1 + // version
@@ -174,6 +181,7 @@ pub trait Domain {
     fn extract_esk(out_plaintext: &[u8; OUT_PLAINTEXT_SIZE]) -> Option<Self::EphemeralSecretKey>;
 }
 
+#[cfg(feature = "alloc")]
 pub trait BatchDomain: Domain {
     /// Computes `Self::kdf` on a batch of items.
     ///