diff --git a/Cargo.toml b/Cargo.toml
index 0018c5b0..66426a6a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -15,10 +15,11 @@ edition = "2018"
 [dependencies]
 http = "0.2.1"
 js_int = { version = "0.1.4", features = ["serde"] }
-ruma-api = "0.15.0"
-ruma-events = "0.18.0"
-ruma-identifiers = "0.14.1"
-serde = { version = "1.0.105", features = ["derive"] }
-serde_json = "1.0.50"
+ruma-api = "0.16.0-rc.1"
+ruma-events = "0.19.0-rc.1"
+ruma-identifiers = "0.15.1"
+ruma-serde = "0.1.0"
+serde = { version = "1.0.106", features = ["derive"] }
+serde_json = "1.0.51"
 strum = { version = "0.18.0", features = ["derive"] }
 url = { version = "2.1.1", features = ["serde"] }
diff --git a/src/lib.rs b/src/lib.rs
index 7c2ed9c0..375c159b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -12,6 +12,4 @@ pub mod error;
 pub mod r0;
 pub mod unversioned;
 
-mod serde;
-
 pub use error::Error;
diff --git a/src/r0/account/register.rs b/src/r0/account/register.rs
index 9b11340d..f517f4ca 100644
--- a/src/r0/account/register.rs
+++ b/src/r0/account/register.rs
@@ -55,7 +55,7 @@ ruma_api! {
         pub kind: Option<RegistrationKind>,
         /// If `true`, an `access_token` and `device_id` should not be returned
         /// from this call, therefore preventing an automatic login.
-        #[serde(default, skip_serializing_if = "crate::serde::is_default")]
+        #[serde(default, skip_serializing_if = "ruma_serde::is_default")]
         pub inhibit_login: bool,
     }
 
diff --git a/src/r0/account/request_openid_token.rs b/src/r0/account/request_openid_token.rs
index 637524a5..ee5166d5 100644
--- a/src/r0/account/request_openid_token.rs
+++ b/src/r0/account/request_openid_token.rs
@@ -30,7 +30,7 @@ ruma_api! {
         /// Homeserver domain for verification of user's identity.
         pub matrix_server_name: String,
         /// Seconds until token expiration.
-        #[serde(with = "crate::serde::duration::secs")]
+        #[serde(with = "ruma_serde::duration::secs")]
         pub expires_in: Duration,
     }
 
diff --git a/src/r0/contact/get_contacts.rs b/src/r0/contact/get_contacts.rs
index 63b31303..06834c64 100644
--- a/src/r0/contact/get_contacts.rs
+++ b/src/r0/contact/get_contacts.rs
@@ -38,10 +38,10 @@ pub struct ThirdPartyIdentifier {
     /// The medium of third party identifier.
     pub medium: Medium,
     /// The time when the identifier was validated by the identity server.
-    #[serde(with = "crate::serde::time::ms_since_unix_epoch")]
+    #[serde(with = "ruma_serde::time::ms_since_unix_epoch")]
     pub validated_at: SystemTime,
     /// The time when the homeserver associated the third party identifier with the user.
-    #[serde(with = "crate::serde::time::ms_since_unix_epoch")]
+    #[serde(with = "ruma_serde::time::ms_since_unix_epoch")]
     pub added_at: SystemTime,
 }
 
diff --git a/src/r0/device.rs b/src/r0/device.rs
index 39523f2e..6e0a8620 100644
--- a/src/r0/device.rs
+++ b/src/r0/device.rs
@@ -22,7 +22,7 @@ pub struct Device {
     pub ip: Option<String>,
     /// Unix timestamp that the session was last active.
     #[serde(
-        with = "crate::serde::time::opt_ms_since_unix_epoch",
+        with = "ruma_serde::time::opt_ms_since_unix_epoch",
         default,
         skip_serializing_if = "Option::is_none"
     )]
diff --git a/src/r0/directory/get_public_rooms_filtered.rs b/src/r0/directory/get_public_rooms_filtered.rs
index b3302f58..3deb6565 100644
--- a/src/r0/directory/get_public_rooms_filtered.rs
+++ b/src/r0/directory/get_public_rooms_filtered.rs
@@ -40,7 +40,7 @@ ruma_api! {
         #[serde(skip_serializing_if = "Option::is_none")]
         pub filter: Option<Filter>,
         /// Network to fetch the public room lists from.
-        #[serde(flatten, skip_serializing_if = "crate::serde::is_default")]
+        #[serde(flatten, skip_serializing_if = "ruma_serde::is_default")]
         pub room_network: RoomNetwork,
     }
 
diff --git a/src/r0/keys/claim_keys.rs b/src/r0/keys/claim_keys.rs
index 3b4dd450..70b5a7ec 100644
--- a/src/r0/keys/claim_keys.rs
+++ b/src/r0/keys/claim_keys.rs
@@ -24,7 +24,7 @@ ruma_api! {
         /// The time (in milliseconds) to wait when downloading keys from remote servers.
         /// 10 seconds is the recommended default.
         #[serde(
-            with = "crate::serde::duration::opt_ms",
+            with = "ruma_serde::duration::opt_ms",
             default,
             skip_serializing_if = "Option::is_none",
         )]
diff --git a/src/r0/keys/get_keys.rs b/src/r0/keys/get_keys.rs
index 98628261..b9e3ecb4 100644
--- a/src/r0/keys/get_keys.rs
+++ b/src/r0/keys/get_keys.rs
@@ -22,7 +22,7 @@ ruma_api! {
         /// The time (in milliseconds) to wait when downloading keys from remote servers.
         /// 10 seconds is the recommended default.
         #[serde(
-            with = "crate::serde::duration::opt_ms",
+            with = "ruma_serde::duration::opt_ms",
             default,
             skip_serializing_if = "Option::is_none",
         )]
diff --git a/src/r0/media/get_media_preview.rs b/src/r0/media/get_media_preview.rs
index 118c09b6..b517d21d 100644
--- a/src/r0/media/get_media_preview.rs
+++ b/src/r0/media/get_media_preview.rs
@@ -21,7 +21,7 @@ ruma_api! {
         pub url: String,
         /// Preferred point in time (in milliseconds) to return a preview for.
         #[ruma_api(query)]
-        #[serde(with = "crate::serde::time::ms_since_unix_epoch")]
+        #[serde(with = "ruma_serde::time::ms_since_unix_epoch")]
         pub ts: SystemTime,
     }
 
diff --git a/src/r0/message/get_message_events.rs b/src/r0/message/get_message_events.rs
index 3d7923ff..e5220d2a 100644
--- a/src/r0/message/get_message_events.rs
+++ b/src/r0/message/get_message_events.rs
@@ -49,7 +49,7 @@ ruma_api! {
         /// A RoomEventFilter to filter returned events with.
         #[ruma_api(query)]
         #[serde(
-            with = "crate::serde::json_string",
+            with = "ruma_serde::json_string",
             default,
             skip_serializing_if = "Option::is_none"
         )]
diff --git a/src/r0/presence/get_presence.rs b/src/r0/presence/get_presence.rs
index 6424435b..b6e02d6e 100644
--- a/src/r0/presence/get_presence.rs
+++ b/src/r0/presence/get_presence.rs
@@ -31,7 +31,7 @@ ruma_api! {
         pub currently_active: Option<bool>,
         /// The length of time in milliseconds since an action was performed by the user.
         #[serde(
-            with = "crate::serde::duration::opt_ms",
+            with = "ruma_serde::duration::opt_ms",
             default,
             skip_serializing_if = "Option::is_none",
         )]
diff --git a/src/r0/push/get_notifications.rs b/src/r0/push/get_notifications.rs
index f26a60fd..de263b96 100644
--- a/src/r0/push/get_notifications.rs
+++ b/src/r0/push/get_notifications.rs
@@ -74,6 +74,6 @@ pub struct Notification {
     pub room_id: RoomId,
 
     /// The time at which the event notification was sent, in milliseconds.
-    #[serde(with = "crate::serde::time::ms_since_unix_epoch")]
+    #[serde(with = "ruma_serde::time::ms_since_unix_epoch")]
     pub ts: SystemTime,
 }
diff --git a/src/r0/server/get_user_info.rs b/src/r0/server/get_user_info.rs
index c07d1985..5c3a5dd9 100644
--- a/src/r0/server/get_user_info.rs
+++ b/src/r0/server/get_user_info.rs
@@ -38,7 +38,7 @@ pub struct ConnectionInfo {
     /// Most recently seen IP address of the session.
     pub ip: String,
     /// Time when that the session was last active.
-    #[serde(with = "crate::serde::time::ms_since_unix_epoch")]
+    #[serde(with = "ruma_serde::time::ms_since_unix_epoch")]
     pub last_seen: SystemTime,
     /// User agent string last seen in the session.
     pub user_agent: String,
diff --git a/src/r0/sync/sync_events.rs b/src/r0/sync/sync_events.rs
index c95e934b..cb6200e2 100644
--- a/src/r0/sync/sync_events.rs
+++ b/src/r0/sync/sync_events.rs
@@ -17,10 +17,7 @@ use ruma_events::{
 use ruma_identifiers::RoomId;
 use serde::{Deserialize, Serialize};
 
-use crate::{
-    r0::{filter::FilterDefinition, keys::KeyAlgorithm},
-    serde::is_default,
-};
+use crate::r0::{filter::FilterDefinition, keys::KeyAlgorithm};
 
 ruma_api! {
     metadata {
@@ -45,16 +42,16 @@ ruma_api! {
         #[ruma_api(query)]
         pub since: Option<String>,
         /// Controls whether to include the full state for all rooms the user is a member of.
-        #[serde(default, skip_serializing_if = "is_default")]
+        #[serde(default, skip_serializing_if = "ruma_serde::is_default")]
         #[ruma_api(query)]
         pub full_state: bool,
         /// Controls whether the client is automatically marked as online by polling this API.
-        #[serde(default, skip_serializing_if = "is_default")]
+        #[serde(default, skip_serializing_if = "ruma_serde::is_default")]
         #[ruma_api(query)]
         pub set_presence: SetPresence,
         /// The maximum time to poll in milliseconds before returning this request.
         #[serde(
-            with = "crate::serde::duration::opt_ms",
+            with = "ruma_serde::duration::opt_ms",
             default,
             skip_serializing_if = "Option::is_none",
         )]
@@ -122,7 +119,7 @@ pub enum Filter {
     // FilterDefinition is the first variant, JSON decoding is attempted first which is almost
     // functionally equivalent to looking at whether the first symbol is a '{' as the spec says.
     // (there are probably some corner cases like leading whitespace)
-    #[serde(with = "crate::serde::json_string")]
+    #[serde(with = "ruma_serde::json_string")]
     /// A complete filter definition serialized to JSON.
     FilterDefinition(FilterDefinition),
     /// The ID of a filter saved on the server.
diff --git a/src/r0/typing/create_typing_event.rs b/src/r0/typing/create_typing_event.rs
index 3731ad02..6d1a4d84 100644
--- a/src/r0/typing/create_typing_event.rs
+++ b/src/r0/typing/create_typing_event.rs
@@ -21,7 +21,7 @@ ruma_api! {
         pub room_id: RoomId,
         /// The length of time in milliseconds to mark this user as typing.
         #[serde(
-            with = "crate::serde::duration::opt_ms",
+            with = "ruma_serde::duration::opt_ms",
             default,
             skip_serializing_if = "Option::is_none",
         )]
diff --git a/src/r0/voip/get_turn_server_info.rs b/src/r0/voip/get_turn_server_info.rs
index 5e83b58f..420a3382 100644
--- a/src/r0/voip/get_turn_server_info.rs
+++ b/src/r0/voip/get_turn_server_info.rs
@@ -20,7 +20,7 @@ ruma_api! {
         /// The password to use.
         pub password: String,
         /// The time-to-live in seconds.
-        #[serde(with = "crate::serde::duration::secs")]
+        #[serde(with = "ruma_serde::duration::secs")]
         pub ttl: Duration,
         /// A list of TURN URIs.
         pub uris: Vec<String>,
diff --git a/src/serde.rs b/src/serde.rs
deleted file mode 100644
index 79c08e92..00000000
--- a/src/serde.rs
+++ /dev/null
@@ -1,9 +0,0 @@
-//! Modules to hold functions for de-/serializing remote types
-
-pub mod duration;
-pub mod json_string;
-pub mod time;
-
-pub fn is_default<T: Default + PartialEq>(val: &T) -> bool {
-    val == &T::default()
-}
diff --git a/src/serde/duration.rs b/src/serde/duration.rs
deleted file mode 100644
index d8c895fa..00000000
--- a/src/serde/duration.rs
+++ /dev/null
@@ -1,4 +0,0 @@
-//! De-/serialization functions for `std::time::Duration` objects
-
-pub mod opt_ms;
-pub mod secs;
diff --git a/src/serde/duration/opt_ms.rs b/src/serde/duration/opt_ms.rs
deleted file mode 100644
index 1e8d6462..00000000
--- a/src/serde/duration/opt_ms.rs
+++ /dev/null
@@ -1,102 +0,0 @@
-//! De-/serialization functions for `Option<std::time::Duration>` objects represented as milliseconds.
-//! Delegates to `js_int::UInt` to ensure integer size is within bounds.
-
-use std::{convert::TryFrom, time::Duration};
-
-use js_int::UInt;
-use serde::{
-    de::{Deserialize, Deserializer},
-    ser::{Error, Serialize, Serializer},
-};
-
-/// Serialize an Option<Duration>.
-///
-/// Will fail if integer is greater than the maximum integer that can be
-/// unambiguously represented by an f64.
-pub fn serialize<S>(opt_duration: &Option<Duration>, serializer: S) -> Result<S::Ok, S::Error>
-where
-    S: Serializer,
-{
-    match opt_duration {
-        Some(duration) => match UInt::try_from(duration.as_millis()) {
-            Ok(uint) => uint.serialize(serializer),
-            Err(err) => Err(S::Error::custom(err)),
-        },
-        None => serializer.serialize_none(),
-    }
-}
-
-/// Deserializes an Option<Duration>.
-///
-/// Will fail if integer is greater than the maximum integer that can be
-/// unambiguously represented by an f64.
-pub fn deserialize<'de, D>(deserializer: D) -> Result<Option<Duration>, D::Error>
-where
-    D: Deserializer<'de>,
-{
-    Ok(Option::<UInt>::deserialize(deserializer)?
-        .map(|millis| Duration::from_millis(millis.into())))
-}
-
-#[cfg(test)]
-mod tests {
-    use std::time::Duration;
-
-    use serde::{Deserialize, Serialize};
-    use serde_json::json;
-
-    #[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
-    struct DurationTest {
-        #[serde(with = "super", default, skip_serializing_if = "Option::is_none")]
-        timeout: Option<Duration>,
-    }
-
-    #[test]
-    fn test_deserialize_some() {
-        let json = json!({ "timeout": 3000 });
-
-        assert_eq!(
-            serde_json::from_value::<DurationTest>(json).unwrap(),
-            DurationTest {
-                timeout: Some(Duration::from_millis(3000))
-            },
-        );
-    }
-
-    #[test]
-    fn test_deserialize_none_by_absence() {
-        let json = json!({});
-
-        assert_eq!(
-            serde_json::from_value::<DurationTest>(json).unwrap(),
-            DurationTest { timeout: None },
-        );
-    }
-
-    #[test]
-    fn test_deserialize_none_by_null() {
-        let json = json!({ "timeout": null });
-
-        assert_eq!(
-            serde_json::from_value::<DurationTest>(json).unwrap(),
-            DurationTest { timeout: None },
-        );
-    }
-
-    #[test]
-    fn test_serialize_some() {
-        let request = DurationTest {
-            timeout: Some(Duration::new(2, 0)),
-        };
-        assert_eq!(
-            serde_json::to_value(&request).unwrap(),
-            json!({ "timeout": 2000 })
-        );
-    }
-
-    #[test]
-    fn test_serialize_none() {
-        let request = DurationTest { timeout: None };
-        assert_eq!(serde_json::to_value(&request).unwrap(), json!({}));
-    }
-}
diff --git a/src/serde/duration/secs.rs b/src/serde/duration/secs.rs
deleted file mode 100644
index 830eb4d5..00000000
--- a/src/serde/duration/secs.rs
+++ /dev/null
@@ -1,69 +0,0 @@
-//! De-/serialization functions for `Option<std::time::Duration>` objects represented as milliseconds.
-//! Delegates to `js_int::UInt` to ensure integer size is within bounds.
-
-use std::{convert::TryFrom, time::Duration};
-
-use js_int::UInt;
-use serde::{
-    de::{Deserialize, Deserializer},
-    ser::{Error, Serialize, Serializer},
-};
-
-/// Serializes a Duration to an integer representing seconds.
-///
-/// Will fail if integer is greater than the maximum integer that can be
-/// unambiguously represented by an f64.
-pub fn serialize<S>(duration: &Duration, serializer: S) -> Result<S::Ok, S::Error>
-where
-    S: Serializer,
-{
-    match UInt::try_from(duration.as_secs()) {
-        Ok(uint) => uint.serialize(serializer),
-        Err(err) => Err(S::Error::custom(err)),
-    }
-}
-
-/// Deserializes an integer representing seconds into a Duration.
-///
-/// Will fail if integer is greater than the maximum integer that can be
-/// unambiguously represented by an f64.
-pub fn deserialize<'de, D>(deserializer: D) -> Result<Duration, D::Error>
-where
-    D: Deserializer<'de>,
-{
-    UInt::deserialize(deserializer).map(|secs| Duration::from_secs(secs.into()))
-}
-
-#[cfg(test)]
-mod tests {
-    use std::time::Duration;
-
-    use serde::{Deserialize, Serialize};
-    use serde_json::json;
-
-    #[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
-    struct DurationTest {
-        #[serde(with = "super")]
-        timeout: Duration,
-    }
-
-    #[test]
-    fn test_deserialize() {
-        let json = json!({ "timeout": 3 });
-
-        assert_eq!(
-            serde_json::from_value::<DurationTest>(json).unwrap(),
-            DurationTest {
-                timeout: Duration::from_secs(3)
-            },
-        );
-    }
-
-    #[test]
-    fn test_serialize() {
-        let test = DurationTest {
-            timeout: Duration::from_millis(7000),
-        };
-        assert_eq!(serde_json::to_value(test).unwrap(), json!({ "timeout": 7 }),);
-    }
-}
diff --git a/src/serde/json_string.rs b/src/serde/json_string.rs
deleted file mode 100644
index e5fabe70..00000000
--- a/src/serde/json_string.rs
+++ /dev/null
@@ -1,24 +0,0 @@
-//! De-/serialization functions to and from json strings, allows the type to be used as a query string.
-
-use serde::{
-    de::{Deserialize, DeserializeOwned, Deserializer, Error as _},
-    ser::{Error as _, Serialize, Serializer},
-};
-
-pub fn serialize<T, S>(filter: T, serializer: S) -> Result<S::Ok, S::Error>
-where
-    T: Serialize,
-    S: Serializer,
-{
-    let json = serde_json::to_string(&filter).map_err(S::Error::custom)?;
-    serializer.serialize_str(&json)
-}
-
-pub fn deserialize<'de, T, D>(deserializer: D) -> Result<T, D::Error>
-where
-    T: DeserializeOwned,
-    D: Deserializer<'de>,
-{
-    let s = String::deserialize(deserializer)?;
-    serde_json::from_str(&s).map_err(D::Error::custom)
-}
diff --git a/src/serde/time.rs b/src/serde/time.rs
deleted file mode 100644
index e60bb839..00000000
--- a/src/serde/time.rs
+++ /dev/null
@@ -1,4 +0,0 @@
-//! De-/serialization functions for `std::time::SystemTime` objects
-
-pub mod ms_since_unix_epoch;
-pub mod opt_ms_since_unix_epoch;
diff --git a/src/serde/time/ms_since_unix_epoch.rs b/src/serde/time/ms_since_unix_epoch.rs
deleted file mode 100644
index ea1b79cc..00000000
--- a/src/serde/time/ms_since_unix_epoch.rs
+++ /dev/null
@@ -1,78 +0,0 @@
-//! De-/serialization functions for `std::time::SystemTime` objects represented as milliseconds
-//! since the UNIX epoch. Delegates to `js_int::UInt` to ensure integer size is within bounds.
-
-use std::{
-    convert::TryFrom,
-    time::{Duration, SystemTime, UNIX_EPOCH},
-};
-
-use js_int::UInt;
-use serde::{
-    de::{Deserialize, Deserializer},
-    ser::{Error, Serialize, Serializer},
-};
-
-/// Serialize a SystemTime.
-///
-/// Will fail if integer is greater than the maximum integer that can be unambiguously represented
-/// by an f64.
-pub fn serialize<S>(time: &SystemTime, serializer: S) -> Result<S::Ok, S::Error>
-where
-    S: Serializer,
-{
-    // If this unwrap fails, the system this is executed is completely broken.
-    let time_since_epoch = time.duration_since(UNIX_EPOCH).unwrap();
-    match UInt::try_from(time_since_epoch.as_millis()) {
-        Ok(uint) => uint.serialize(serializer),
-        Err(err) => Err(S::Error::custom(err)),
-    }
-}
-
-/// Deserializes a SystemTime.
-///
-/// Will fail if integer is greater than the maximum integer that can be unambiguously represented
-/// by an f64.
-pub fn deserialize<'de, D>(deserializer: D) -> Result<SystemTime, D::Error>
-where
-    D: Deserializer<'de>,
-{
-    let millis = UInt::deserialize(deserializer)?;
-    Ok(UNIX_EPOCH + Duration::from_millis(millis.into()))
-}
-
-#[cfg(test)]
-mod tests {
-    use std::time::{Duration, SystemTime, UNIX_EPOCH};
-
-    use serde::{Deserialize, Serialize};
-    use serde_json::json;
-
-    #[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
-    struct SystemTimeTest {
-        #[serde(with = "super")]
-        timestamp: SystemTime,
-    }
-
-    #[test]
-    fn test_deserialize() {
-        let json = json!({ "timestamp": 3000 });
-
-        assert_eq!(
-            serde_json::from_value::<SystemTimeTest>(json).unwrap(),
-            SystemTimeTest {
-                timestamp: UNIX_EPOCH + Duration::from_millis(3000),
-            },
-        );
-    }
-
-    #[test]
-    fn test_serialize() {
-        let request = SystemTimeTest {
-            timestamp: UNIX_EPOCH + Duration::new(2, 0),
-        };
-        assert_eq!(
-            serde_json::to_value(&request).unwrap(),
-            json!({ "timestamp": 2000 })
-        );
-    }
-}
diff --git a/src/serde/time/opt_ms_since_unix_epoch.rs b/src/serde/time/opt_ms_since_unix_epoch.rs
deleted file mode 100644
index 787455ac..00000000
--- a/src/serde/time/opt_ms_since_unix_epoch.rs
+++ /dev/null
@@ -1,100 +0,0 @@
-//! De-/serialization functions for `Option<std::time::SystemTime>` objects represented as
-//! milliseconds since the UNIX epoch. Delegates to `js_int::UInt` to ensure integer size is within
-//! bounds.
-
-use std::time::{Duration, SystemTime, UNIX_EPOCH};
-
-use js_int::UInt;
-use serde::{
-    de::{Deserialize, Deserializer},
-    ser::{Serialize, Serializer},
-};
-
-/// Serialize an `Option<SystemTime>`.
-///
-/// Will fail if integer is greater than the maximum integer that can be unambiguously represented
-/// by an f64.
-pub fn serialize<S>(opt_time: &Option<SystemTime>, serializer: S) -> Result<S::Ok, S::Error>
-where
-    S: Serializer,
-{
-    match opt_time {
-        Some(time) => super::ms_since_unix_epoch::serialize(time, serializer),
-        None => Option::<UInt>::serialize(&None, serializer),
-    }
-}
-
-/// Deserializes an `Option<SystemTime>`.
-///
-/// Will fail if integer is greater than the maximum integer that can be unambiguously represented
-/// by an f64.
-pub fn deserialize<'de, D>(deserializer: D) -> Result<Option<SystemTime>, D::Error>
-where
-    D: Deserializer<'de>,
-{
-    Ok(Option::<UInt>::deserialize(deserializer)?
-        .map(|millis| UNIX_EPOCH + Duration::from_millis(millis.into())))
-}
-
-#[cfg(test)]
-mod tests {
-    use std::time::{Duration, SystemTime, UNIX_EPOCH};
-
-    use serde::{Deserialize, Serialize};
-    use serde_json::json;
-
-    #[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
-    struct SystemTimeTest {
-        #[serde(with = "super", default, skip_serializing_if = "Option::is_none")]
-        timestamp: Option<SystemTime>,
-    }
-
-    #[test]
-    fn test_deserialize_some() {
-        let json = json!({ "timestamp": 3000 });
-
-        assert_eq!(
-            serde_json::from_value::<SystemTimeTest>(json).unwrap(),
-            SystemTimeTest {
-                timestamp: Some(UNIX_EPOCH + Duration::from_millis(3000))
-            },
-        );
-    }
-
-    #[test]
-    fn test_deserialize_none_by_absence() {
-        let json = json!({});
-
-        assert_eq!(
-            serde_json::from_value::<SystemTimeTest>(json).unwrap(),
-            SystemTimeTest { timestamp: None },
-        );
-    }
-
-    #[test]
-    fn test_deserialize_none_by_null() {
-        let json = json!({ "timestamp": null });
-
-        assert_eq!(
-            serde_json::from_value::<SystemTimeTest>(json).unwrap(),
-            SystemTimeTest { timestamp: None },
-        );
-    }
-
-    #[test]
-    fn test_serialize_some() {
-        let request = SystemTimeTest {
-            timestamp: Some(UNIX_EPOCH + Duration::new(2, 0)),
-        };
-        assert_eq!(
-            serde_json::to_value(&request).unwrap(),
-            json!({ "timestamp": 2000 })
-        );
-    }
-
-    #[test]
-    fn test_serialize_none() {
-        let request = SystemTimeTest { timestamp: None };
-        assert_eq!(serde_json::to_value(&request).unwrap(), json!({}));
-    }
-}