diff --git a/core/src/codec.rs b/core/src/codec.rs
index 89f02db0..15b3c8a4 100644
--- a/core/src/codec.rs
+++ b/core/src/codec.rs
@@ -1,6 +1,6 @@
 //! `Ipld` codecs.
-use alloc::{format, string::String, vec::Vec};
-use core::convert::TryFrom;
+use alloc::{string::String, vec::Vec};
+use core::{convert::TryFrom, fmt::Write as _};
 
 use crate::cid::Cid;
 use crate::error::{Result, UnsupportedCodec};
@@ -85,7 +85,10 @@ where
     Ipld: Decode<C> + Encode<C>,
 {
     fn hex(bytes: &[u8]) -> String {
-        bytes.iter().map(|byte| format!("{:02x}", byte)).collect()
+        bytes.iter().fold(String::new(), |mut output, byte| {
+            let _ = write!(output, "{byte:02x}");
+            output
+        })
     }
     let mut bytes = Vec::new();
     data.encode(c, &mut bytes).unwrap();
diff --git a/core/tests/serde_deserialize.rs b/core/tests/serde_deserialize.rs
index 3e67ce2d..205ca60d 100644
--- a/core/tests/serde_deserialize.rs
+++ b/core/tests/serde_deserialize.rs
@@ -143,7 +143,7 @@ fn ipld_deserialize_link() {
 }
 
 #[test]
-#[should_panic(expected = "assertion failed")]
+#[should_panic]
 fn ipld_deserialize_link_not_as_bytes() {
     let cid = Cid::try_from("bafkreie74tgmnxqwojhtumgh5dzfj46gi4mynlfr7dmm7duwzyvnpw7h7m").unwrap();
     let ipld = Ipld::Link(cid);
diff --git a/dag-cbor/tests/serde_interop.rs b/dag-cbor/tests/serde_interop.rs
index 40adaf52..5821f07a 100644
--- a/dag-cbor/tests/serde_interop.rs
+++ b/dag-cbor/tests/serde_interop.rs
@@ -41,8 +41,7 @@ impl Arbitrary for ValueArb {
                     .into_iter()
                     .map(|x| {
                         let slf = Self(x);
-                        let shrunk = slf.shrink().map(|x| x.0).collect::<Vec<_>>();
-                        shrunk
+                        slf.shrink().map(|x| x.0).collect::<Vec<_>>()
                     })
                     .map(Value::Array)
                     .map(Self),