diff --git a/zebra-chain/Cargo.toml b/zebra-chain/Cargo.toml
index bc2db554..f08fc1a0 100644
--- a/zebra-chain/Cargo.toml
+++ b/zebra-chain/Cargo.toml
@@ -18,6 +18,7 @@ rand_core = "0.5.1"
 ripemd160 = "0.8.0"
 secp256k1 = { version = "0.17.2", features = ["serde"] }
 serde = { version = "1", features = ["serde_derive"] }
+# TODO: update to crates.io version when available, #326
 sha2 = {git="https://github.com/RustCrypto/hashes", rev="30b416a", features=["compress"]}
 thiserror = "1"
 x25519-dalek = "0.6"