diff --git a/zebra-chain/src/orchard/keys.rs b/zebra-chain/src/orchard/keys.rs
index 2e11f161b..f1d035d25 100644
--- a/zebra-chain/src/orchard/keys.rs
+++ b/zebra-chain/src/orchard/keys.rs
@@ -410,7 +410,9 @@ impl From<SpendingKey> for IvkCommitRandomness {
     ///
     /// https://zips.z.cash/protocol/protocol.pdf#orchardkeycomponents
     fn from(sk: SpendingKey) -> Self {
-        Self(pallas::Scalar::from_bytes_wide(prf_expand(sk.into(), &[8])))
+        let scalar = pallas::Scalar::from_bytes_wide(&prf_expand(sk.into(), &[&[8]]));
+
+        Self(scalar)
     }
 }
 
diff --git a/zebra-chain/src/orchard/keys/tests.rs b/zebra-chain/src/orchard/keys/tests.rs
index 8b8f43228..ece24cbc3 100644
--- a/zebra-chain/src/orchard/keys/tests.rs
+++ b/zebra-chain/src/orchard/keys/tests.rs
@@ -12,10 +12,10 @@ impl Arbitrary for TransmissionKey {
         (any::<SpendingKey>())
             .prop_map(|spending_key| {
                 let spend_authorizing_key = SpendAuthorizingKey::from(spending_key);
-                let proof_authorizing_key = ProofAuthorizingKey::from(spending_key);
 
-                let authorizing_key = AuthorizingKey::from(spend_authorizing_key);
-                let nullifier_deriving_key = NullifierDerivingKey::from(proof_authorizing_key);
+                let spend_validating_key = SpendValidatingKey::from(spending_key);
+                let nullifier_deriving_key = NullifierDerivingKey::from(spending_key);
+                let ivk_commit_randomness = IvkCommitRandomness::from();
 
                 let incoming_viewing_key =
                     IncomingViewingKey::from((authorizing_key, nullifier_deriving_key));