diff --git a/CHANGELOG.md b/CHANGELOG.md
index 78563dabf..6ba38b967 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,8 @@
 # Changelog
 
+## 0.10.2 (TBD)
+- Implement `core::error::Error` for error types (#341).
+
 ## 0.10.1 (2024-10-30)
 - Fixed partition hashing and add logging to aux trace building (#338).
 
diff --git a/air/src/errors.rs b/air/src/errors.rs
index 2f0fa1665..38196ba7d 100644
--- a/air/src/errors.rs
+++ b/air/src/errors.rs
@@ -42,3 +42,5 @@ impl fmt::Display for AssertionError {
         }
     }
 }
+
+impl core::error::Error for AssertionError {}
diff --git a/crypto/src/errors.rs b/crypto/src/errors.rs
index 5e4f3a6da..637b90c99 100644
--- a/crypto/src/errors.rs
+++ b/crypto/src/errors.rs
@@ -61,6 +61,8 @@ impl fmt::Display for MerkleTreeError {
     }
 }
 
+impl core::error::Error for MerkleTreeError {}
+
 // RANDOM COIN ERROR
 // ================================================================================================
 
@@ -89,3 +91,5 @@ impl fmt::Display for RandomCoinError {
         }
     }
 }
+
+impl core::error::Error for RandomCoinError {}
diff --git a/fri/src/errors.rs b/fri/src/errors.rs
index 7961b8831..2947b17a8 100644
--- a/fri/src/errors.rs
+++ b/fri/src/errors.rs
@@ -73,3 +73,5 @@ impl fmt::Display for VerifierError {
         }
     }
 }
+
+impl core::error::Error for VerifierError {}
diff --git a/prover/src/errors.rs b/prover/src/errors.rs
index a0d01a233..6fd560582 100644
--- a/prover/src/errors.rs
+++ b/prover/src/errors.rs
@@ -39,3 +39,5 @@ impl fmt::Display for ProverError {
         }
     }
 }
+
+impl core::error::Error for ProverError {}
diff --git a/utils/core/src/errors.rs b/utils/core/src/errors.rs
index 52df2b007..1bba975bf 100644
--- a/utils/core/src/errors.rs
+++ b/utils/core/src/errors.rs
@@ -32,3 +32,5 @@ impl fmt::Display for DeserializationError {
         }
     }
 }
+
+impl core::error::Error for DeserializationError {}
diff --git a/utils/core/src/serde/mod.rs b/utils/core/src/serde/mod.rs
index edf9ba1c8..90ac01b6d 100644
--- a/utils/core/src/serde/mod.rs
+++ b/utils/core/src/serde/mod.rs
@@ -344,7 +344,7 @@ impl Serializable for str {
     }
 
     fn get_size_hint(&self) -> usize {
-        self.len().get_size_hint() + self.as_bytes().len()
+        self.len().get_size_hint() + self.len()
     }
 }
 
@@ -355,7 +355,7 @@ impl Serializable for String {
     }
 
     fn get_size_hint(&self) -> usize {
-        self.len().get_size_hint() + self.as_bytes().len()
+        self.len().get_size_hint() + self.len()
     }
 }
 
diff --git a/verifier/src/errors.rs b/verifier/src/errors.rs
index e1b072db5..fadaee1fa 100644
--- a/verifier/src/errors.rs
+++ b/verifier/src/errors.rs
@@ -99,3 +99,5 @@ impl fmt::Display for VerifierError {
         }
     }
 }
+
+impl core::error::Error for VerifierError {}