diff --git a/crypto/dalek-ff-group/Cargo.toml b/crypto/dalek-ff-group/Cargo.toml
index bea86d89..3403282b 100644
--- a/crypto/dalek-ff-group/Cargo.toml
+++ b/crypto/dalek-ff-group/Cargo.toml
@@ -29,3 +29,6 @@ curve25519-dalek = "^3.2"
 
 [dev-dependencies]
 ff-group-tests = { path = "../ff-group-tests" }
+
+[features]
+black_box = []
diff --git a/crypto/dalek-ff-group/src/lib.rs b/crypto/dalek-ff-group/src/lib.rs
index 56aaf275..4b5d5fc3 100644
--- a/crypto/dalek-ff-group/src/lib.rs
+++ b/crypto/dalek-ff-group/src/lib.rs
@@ -43,7 +43,14 @@ pub mod field;
 
 // Convert a boolean to a Choice in a *presumably* constant time manner
 fn choice(value: bool) -> Choice {
-  Choice::from(u8::from(value))
+  #[cfg(not(feature = "black_box"))]
+  let res = Choice::from(u8::from(value));
+  #[cfg(feature = "black_box")]
+  let res = {
+    use core::hint::black_box;
+    Choice::from(black_box(u8::from(black_box(value))))
+  };
+  res
 }
 
 macro_rules! deref_borrow {
diff --git a/processor/Cargo.toml b/processor/Cargo.toml
index f86fb7a6..127d5bd6 100644
--- a/processor/Cargo.toml
+++ b/processor/Cargo.toml
@@ -24,7 +24,7 @@ group = "0.12"
 curve25519-dalek = { version = "3", features = ["std"] }
 
 transcript = { package = "flexible-transcript", path = "../crypto/transcript", features = ["recommended"] }
-dalek-ff-group = { path = "../crypto/dalek-ff-group" }
+dalek-ff-group = { path = "../crypto/dalek-ff-group", features = ["black_box"] }
 frost = { package = "modular-frost", path = "../crypto/frost", features = ["ed25519"] }
 
 monero-serai = { path = "../coins/monero", features = ["multisig"] }