diff --git a/crates/web5/src/credentials/verifiable_credential_1_1.rs b/crates/web5/src/credentials/verifiable_credential_1_1.rs
index 2eb96dc8..79768d1f 100644
--- a/crates/web5/src/credentials/verifiable_credential_1_1.rs
+++ b/crates/web5/src/credentials/verifiable_credential_1_1.rs
@@ -2,7 +2,7 @@ use super::{CredentialError, Result as ResultOld};
 use crate::errors::{Result, Web5Error};
 use crate::json::{FromJson, JsonObject, ToJson};
 use crate::rfc3339::{
-    deserialize_option_system_time, deserialize_system_time, serialize_option_system_time,
+    deserialize_optional_system_time, deserialize_system_time, serialize_optional_system_time,
     serialize_system_time,
 };
 use crate::{
@@ -118,8 +118,8 @@ pub struct VerifiableCredential {
     pub issuance_date: SystemTime,
     #[serde(
         rename = "expirationDate",
-        serialize_with = "serialize_option_system_time",
-        deserialize_with = "deserialize_option_system_time"
+        serialize_with = "serialize_optional_system_time",
+        deserialize_with = "deserialize_optional_system_time"
     )]
     pub expiration_date: Option<SystemTime>,
 }
@@ -448,14 +448,14 @@ struct JwtPayloadVerifiableCredential {
     issuer: Option<Issuer>,
     #[serde(
         rename = "issuanceDate",
-        serialize_with = "serialize_option_system_time",
-        deserialize_with = "deserialize_option_system_time"
+        serialize_with = "serialize_optional_system_time",
+        deserialize_with = "deserialize_optional_system_time"
     )]
     issuance_date: Option<SystemTime>,
     #[serde(
         rename = "expirationDate",
-        serialize_with = "serialize_option_system_time",
-        deserialize_with = "deserialize_option_system_time"
+        serialize_with = "serialize_optional_system_time",
+        deserialize_with = "deserialize_optional_system_time"
     )]
     expiration_date: Option<SystemTime>,
     #[serde(skip_serializing_if = "Option::is_none", rename = "credentialSubject")]
diff --git a/crates/web5/src/rfc3339.rs b/crates/web5/src/rfc3339.rs
index 2f77896a..9025ffad 100644
--- a/crates/web5/src/rfc3339.rs
+++ b/crates/web5/src/rfc3339.rs
@@ -25,7 +25,7 @@ where
     Ok(datetime.with_timezone(&Utc).into())
 }
 
-pub(crate) fn serialize_option_system_time<S>(
+pub(crate) fn serialize_optional_system_time<S>(
     time: &Option<SystemTime>,
     serializer: S,
 ) -> std::result::Result<S::Ok, S::Error>
@@ -38,7 +38,7 @@ where
     }
 }
 
-pub(crate) fn deserialize_option_system_time<'de, D>(
+pub(crate) fn deserialize_optional_system_time<'de, D>(
     deserializer: D,
 ) -> std::result::Result<Option<SystemTime>, D::Error>
 where