diff --git a/CHANGELOG.md b/CHANGELOG.md
index fcd131ce..fa449ab0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,10 @@ Breaking changes:
   * Remove `inhibit_login` request field, make `access_token` and `device_id` response fields optional (added in r0.4.0)
   * Remove deprecated `home_server` response field (removed in r0.4.0)
 * Update `r0::contact::get_contacts` endpoint to r0.6.0
+* Change `UInt` timestamps to `SystemTime` in:
+  * `media::get_media_preview`
+  * `push::get_notifications`
+  * `server::get_user_info`
 
 Improvements:
 
diff --git a/src/r0/media/get_media_preview.rs b/src/r0/media/get_media_preview.rs
index 13dd4a5c..118c09b6 100644
--- a/src/r0/media/get_media_preview.rs
+++ b/src/r0/media/get_media_preview.rs
@@ -1,6 +1,7 @@
 //! [GET /_matrix/media/r0/preview_url](https://matrix.org/docs/spec/client_server/r0.6.0#get-matrix-media-r0-preview-url)
 
-use js_int::UInt;
+use std::time::SystemTime;
+
 use ruma_api::ruma_api;
 use serde_json::Value;
 
@@ -20,7 +21,8 @@ ruma_api! {
         pub url: String,
         /// Preferred point in time (in milliseconds) to return a preview for.
         #[ruma_api(query)]
-        pub ts: UInt,
+        #[serde(with = "crate::serde::time::ms_since_unix_epoch")]
+        pub ts: SystemTime,
     }
 
     response {
diff --git a/src/r0/push/get_notifications.rs b/src/r0/push/get_notifications.rs
index 6774e8a2..f26a60fd 100644
--- a/src/r0/push/get_notifications.rs
+++ b/src/r0/push/get_notifications.rs
@@ -1,5 +1,7 @@
 //! [GET /_matrix/client/r0/notifications](https://matrix.org/docs/spec/client_server/r0.6.0#get-matrix-client-r0-notifications)
 
+use std::time::SystemTime;
+
 use js_int::UInt;
 use ruma_api::{ruma_api, Outgoing};
 use ruma_events::{collections::all, EventResult};
@@ -71,6 +73,7 @@ pub struct Notification {
     /// The ID of the room in which the event was posted.
     pub room_id: RoomId,
 
-    /// The unix timestamp at which the event notification was sent, in milliseconds.
-    pub ts: UInt,
+    /// The time at which the event notification was sent, in milliseconds.
+    #[serde(with = "crate::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 1cb6aef2..c07d1985 100644
--- a/src/r0/server/get_user_info.rs
+++ b/src/r0/server/get_user_info.rs
@@ -1,8 +1,7 @@
 //! [GET /_matrix/client/r0/admin/whois/{userId}](https://matrix.org/docs/spec/client_server/r0.4.0.html#get-matrix-client-r0-admin-whois-userid)
 
-use std::collections::HashMap;
+use std::{collections::HashMap, time::SystemTime};
 
-use js_int::UInt;
 use ruma_api::ruma_api;
 use ruma_identifiers::UserId;
 use serde::{Deserialize, Serialize};
@@ -38,8 +37,9 @@ ruma_api! {
 pub struct ConnectionInfo {
     /// Most recently seen IP address of the session.
     pub ip: String,
-    /// Unix timestamp that the session was last active.
-    pub last_seen: UInt,
+    /// Time when that the session was last active.
+    #[serde(with = "crate::serde::time::ms_since_unix_epoch")]
+    pub last_seen: SystemTime,
     /// User agent string last seen in the session.
     pub user_agent: String,
 }