diff --git a/benches/primitives.rs b/benches/primitives.rs
index 8a40023b..df6747b5 100644
--- a/benches/primitives.rs
+++ b/benches/primitives.rs
@@ -3,7 +3,7 @@ use std::array;
 use criterion::{criterion_group, criterion_main, BenchmarkId, Criterion};
 use ff::Field;
 use orchard::primitives::{
-    poseidon::{self, ConstantLength, OrchardNullifier},
+    poseidon::{self, ConstantLength, P128Pow5T3},
     sinsemilla,
 };
 
@@ -21,7 +21,7 @@ fn bench_primitives(c: &mut Criterion) {
         let message = [pallas::Base::random(rng), pallas::Base::random(rng)];
 
         group.bench_function("2-to-1", |b| {
-            b.iter(|| poseidon::Hash::init(OrchardNullifier, ConstantLength).hash(message))
+            b.iter(|| poseidon::Hash::init(P128Pow5T3, ConstantLength).hash(message))
         });
     }
 
diff --git a/src/circuit.rs b/src/circuit.rs
index ad868c4b..e1ba1c88 100644
--- a/src/circuit.rs
+++ b/src/circuit.rs
@@ -244,7 +244,7 @@ impl plonk::Circuit<pallas::Base> for Circuit {
         // Configuration for the Poseidon hash.
         let poseidon_config = PoseidonChip::configure(
             meta,
-            poseidon::OrchardNullifier,
+            poseidon::P128Pow5T3,
             // We place the state columns after the partial_sbox column so that the
             // pad-and-add region can be layed out more efficiently.
             advices[6..9].try_into().unwrap(),
@@ -499,7 +499,7 @@ impl plonk::Circuit<pallas::Base> for Circuit {
                                 || value.ok_or(plonk::Error::SynthesisError),
                             )?;
                             region.constrain_equal(var, message[i].cell())?;
-                            Ok(Word::<_, _, poseidon::OrchardNullifier, 3, 2>::from_inner(
+                            Ok(Word::<_, _, poseidon::P128Pow5T3, 3, 2>::from_inner(
                                 StateWord::new(var, value),
                             ))
                         };
diff --git a/src/circuit/gadget/poseidon/pow5t3.rs b/src/circuit/gadget/poseidon/pow5t3.rs
index d0e7871f..277432c1 100644
--- a/src/circuit/gadget/poseidon/pow5t3.rs
+++ b/src/circuit/gadget/poseidon/pow5t3.rs
@@ -627,7 +627,7 @@ mod tests {
     use super::{PoseidonInstructions, Pow5T3Chip, Pow5T3Config, StateWord, WIDTH};
     use crate::{
         circuit::gadget::poseidon::{Hash, Word},
-        primitives::poseidon::{self, ConstantLength, OrchardNullifier, Spec},
+        primitives::poseidon::{self, ConstantLength, P128Pow5T3 as OrchardNullifier, Spec},
     };
 
     struct PermuteCircuit {}
diff --git a/src/primitives/poseidon.rs b/src/primitives/poseidon.rs
index b06303a5..f2892d1b 100644
--- a/src/primitives/poseidon.rs
+++ b/src/primitives/poseidon.rs
@@ -15,8 +15,8 @@ pub(crate) mod mds;
 #[cfg(test)]
 pub(crate) mod test_vectors;
 
-mod nullifier;
-pub use nullifier::OrchardNullifier;
+mod p128pow5t3;
+pub use p128pow5t3::P128Pow5T3;
 
 use grain::SboxType;
 
@@ -365,7 +365,7 @@ mod tests {
     use halo2::arithmetic::FieldExt;
     use pasta_curves::pallas;
 
-    use super::{permute, ConstantLength, Hash, OrchardNullifier, Spec};
+    use super::{permute, ConstantLength, Hash, P128Pow5T3 as OrchardNullifier, Spec};
 
     #[test]
     fn orchard_spec_equivalence() {
diff --git a/src/primitives/poseidon/nullifier.rs b/src/primitives/poseidon/p128pow5t3.rs
similarity index 91%
rename from src/primitives/poseidon/nullifier.rs
rename to src/primitives/poseidon/p128pow5t3.rs
index 5ba5d128..44bce101 100644
--- a/src/primitives/poseidon/nullifier.rs
+++ b/src/primitives/poseidon/p128pow5t3.rs
@@ -13,9 +13,9 @@ use super::{
 /// This is conveniently an even number of partial rounds, making it easier to
 /// construct a Halo 2 circuit.
 #[derive(Debug)]
-pub struct OrchardNullifier;
+pub struct P128Pow5T3;
 
-impl Spec<pallas::Base, 3, 2> for OrchardNullifier {
+impl Spec<pallas::Base, 3, 2> for P128Pow5T3 {
     fn full_rounds() -> usize {
         8
     }
@@ -53,9 +53,9 @@ mod tests {
 
     use crate::primitives::poseidon::{permute, ConstantLength, Hash, Spec};
 
-    use super::{OrchardNullifier, MDS, MDS_INV, ROUND_CONSTANTS};
+    use super::{MDS, MDS_INV, ROUND_CONSTANTS};
 
-    /// The same Poseidon specification as poseidon::OrchardNullifier, but constructed
+    /// The same Poseidon specification as poseidon::P128Pow5T3, but constructed
     /// such that its constants will be generated at runtime.
     #[derive(Debug)]
     pub struct P128Pow5T3<F: FieldExt> {
@@ -166,7 +166,7 @@ mod tests {
 
     #[test]
     fn permute_test_vectors() {
-        let (round_constants, mds, _) = OrchardNullifier.constants();
+        let (round_constants, mds, _) = super::P128Pow5T3.constants();
 
         for tv in crate::primitives::poseidon::test_vectors::permute() {
             let mut state = [
@@ -175,7 +175,7 @@ mod tests {
                 pallas::Base::from_repr(tv.initial_state[2]).unwrap(),
             ];
 
-            permute::<pallas::Base, OrchardNullifier, 3, 2>(&mut state, &mds, &round_constants);
+            permute::<pallas::Base, super::P128Pow5T3, 3, 2>(&mut state, &mds, &round_constants);
 
             for (expected, actual) in tv.final_state.iter().zip(state.iter()) {
                 assert_eq!(&actual.to_repr(), expected);
@@ -191,7 +191,7 @@ mod tests {
                 pallas::Base::from_repr(tv.input[1]).unwrap(),
             ];
 
-            let result = Hash::init(OrchardNullifier, ConstantLength).hash(message);
+            let result = Hash::init(super::P128Pow5T3, ConstantLength).hash(message);
 
             assert_eq!(result.to_repr(), tv.output);
         }
diff --git a/src/spec.rs b/src/spec.rs
index 15fc1613..ddd394c6 100644
--- a/src/spec.rs
+++ b/src/spec.rs
@@ -212,7 +212,7 @@ pub(crate) fn diversify_hash(d: &[u8; 11]) -> NonIdentityPallasPoint {
 ///
 /// [concreteprfs]: https://zips.z.cash/protocol/nu5.pdf#concreteprfs
 pub(crate) fn prf_nf(nk: pallas::Base, rho: pallas::Base) -> pallas::Base {
-    poseidon::Hash::init(poseidon::OrchardNullifier, poseidon::ConstantLength).hash([nk, rho])
+    poseidon::Hash::init(poseidon::P128Pow5T3, poseidon::ConstantLength).hash([nk, rho])
 }
 
 /// Defined in [Zcash Protocol Spec § 5.4.5.5: Orchard Key Agreement][concreteorchardkeyagreement].