diff --git a/zebra-chain/src/orchard/note/ciphertexts.rs b/zebra-chain/src/orchard/note/ciphertexts.rs
index 5de5be687..b858fbd43 100644
--- a/zebra-chain/src/orchard/note/ciphertexts.rs
+++ b/zebra-chain/src/orchard/note/ciphertexts.rs
@@ -17,6 +17,7 @@ impl fmt::Debug for EncryptedNote {
 }
 
 // These impls all only exist because of array length restrictions.
+// TODO: use const generics https://github.com/ZcashFoundation/zebra/issues/2042
 
 impl Copy for EncryptedNote {}
 
diff --git a/zebra-chain/src/primitives/proofs/halo2.rs b/zebra-chain/src/primitives/proofs/halo2.rs
index 240ba8972..4e90463af 100644
--- a/zebra-chain/src/primitives/proofs/halo2.rs
+++ b/zebra-chain/src/primitives/proofs/halo2.rs
@@ -21,6 +21,7 @@ impl fmt::Debug for Halo2Proof {
 }
 
 // These impls all only exist because of array length restrictions.
+// TODO: use const generics https://github.com/ZcashFoundation/zebra/issues/2042
 
 // impl Copy for Halo2Proof {}