diff --git a/protocol/Cargo.toml b/protocol/Cargo.toml
index 2be5961..80e0a52 100644
--- a/protocol/Cargo.toml
+++ b/protocol/Cargo.toml
@@ -10,15 +10,18 @@ rust-version = "1.63.0"
 
 [features]
 default = ["std"]
-async = ["std", "futures/std"]
-tokio = ["std", "tokio/io-util"]
+# High-level wrappers using futures traits.
+async = ["std", "dep:futures"]
+# High-level wrappers using tokio traits - may affect MSRV requirements.
+tokio = ["std", "dep:tokio"]
 std = ["alloc", "bitcoin/std", "bitcoin_hashes/std", "chacha20-poly1305/std", "rand/std", "rand/std_rng"]
 alloc = ["chacha20-poly1305/alloc"]
 
 [dependencies]
-futures = { version = "0.3.30", default-features = false, optional = true }
-# Must be under 1.39.0 due to MSRV 1.63.0 requirement.
-tokio = { version = ">=1.37.0, <1.39.0", default-features = false, optional = true }
+futures = { version = "0.3.30", default-features = false, optional = true, features = ["std"] }
+# The tokio feature may increase the MSRV beyond 1.63.0
+# depending on which version of tokio is selected by the caller.
+tokio = { version = "1", default-features = false, optional = true, features = ["io-util"] }
 rand = { version = "0.8.0", default-features = false }
 bitcoin = { version = "0.32.4", default-features = false }
 # Depending on hashes directly for HKDF, can drop this and 
diff --git a/protocol/README.md b/protocol/README.md
index f50a969..5938e04 100644
--- a/protocol/README.md
+++ b/protocol/README.md
@@ -15,6 +15,12 @@ The lower-level `Handshake` and `PacketHandler` types can be directly used by ap
 * `async` -- High level wrappers for asynchronous read and write runtimes using agnostic futures-rs traits.
 * `tokio` -- Same wrappers as `async`, but using the popular tokio runtime's specific traits instead of futures-rs.
 
+## Minimum Supported Rust Version (MSRV)
+
+This crate has a baseline MSRV of **1.63.0**.
+
+However, the effective MSRV may be higher depending on the specific versions of dependencies selected by the caller. Currently, tokio is known to affect MSRV when using newer versions with the `tokio` feature flag, but other dependencies may also impact the effective MSRV in the future.
+
 ## Handshake
 
 Alice and Bob initiate a connection by sending three messages to each other to derive a number of shared secrets. Alice begins the connection by deriving a public/private keypair over `secp256k1`, the typical bitcoin curve. Alice is known as the *initiator*. She encodes the public key in the [Elligator Swift](https://eprint.iacr.org/2022/759.pdf) format (64-bytes), optionally pads it with some random garbage bytes, and sends the message to Bob.