diff --git a/CHANGELOG.md b/CHANGELOG.md
index 522eb0f..a6afe91 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,7 +2,9 @@
 
 ## [Unreleased][]
 
--
+### Changed
+
+- Update `cbor-smol` dependency to v0.5.0
 
 [Unreleased]: https://github.com/trussed-dev/trussed-staging/compare/v0.3.0...HEAD
 
diff --git a/Cargo.toml b/Cargo.toml
index 31c8c0a..6c34bdd 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -39,7 +39,7 @@ iso7816 = "0.1.1"
 hmac = "0.12.1"
 rand = { version = "0.8.5", default-features = false }
 littlefs2 = "0.4.0"
-cbor-smol = "0.4.0"
+cbor-smol = { version = "0.5.0", features = ["heapless-bytes-v0-3"] }
 serde_bytes = { version = "0.11.12", default-features = false }
 trussed-rsa-alloc = "0.2.1"
 postcard = "0.7.3"
diff --git a/src/staging.rs b/src/staging.rs
index 61d183b..6b960ea 100644
--- a/src/staging.rs
+++ b/src/staging.rs
@@ -484,7 +484,9 @@ impl UnsealedKey {
     // encoding: |map(2) | text(1) | "d" | bytes (len as u16) | MAX_SERIALIZED_KEY_LENGTH | data
     // | text(1) | "k" | array(1 if core, 2 if se050) | discriminator | (discriminiator) if se050 |
     fn serialize(&self) -> Bytes<{ MAX_SERIALIZED_KEY_LENGTH + 11 + HPKE_OVERHEAD }> {
-        cbor_smol::cbor_serialize_bytes(&self).unwrap()
+        let mut data = Bytes::new();
+        cbor_smol::cbor_serialize_to(&self, &mut data).unwrap();
+        data
     }
     fn try_deserialize(data: &[u8]) -> Result<Self, Error> {
         cbor_smol::cbor_deserialize(data).map_err(|_| Error::CborError)