diff --git a/crates/ruma-client-api/CHANGELOG.md b/crates/ruma-client-api/CHANGELOG.md
index 5c33c156..1b3425f0 100644
--- a/crates/ruma-client-api/CHANGELOG.md
+++ b/crates/ruma-client-api/CHANGELOG.md
@@ -18,6 +18,7 @@ Improvements:
 * Add support for the pagination direction parameter to `/relations` (MSC3715 / Matrix 1.4)
 * Add support for notifications for threads (MSC3773 / Matrix 1.4)
 * Send CORP headers by default for media responses (MSC3828 / Matrix 1.4)
+* Add support for read receipts for threads (MSC3771 / Matrix 1.4)
 
 # 0.15.1
 
diff --git a/crates/ruma-client-api/src/receipt/create_receipt.rs b/crates/ruma-client-api/src/receipt/create_receipt.rs
index d84843fc..65b89f71 100644
--- a/crates/ruma-client-api/src/receipt/create_receipt.rs
+++ b/crates/ruma-client-api/src/receipt/create_receipt.rs
@@ -7,6 +7,7 @@ pub mod v3 {
 
     use ruma_common::{
         api::ruma_api,
+        events::receipt::ReceiptThread,
         serde::{OrdAsRefStr, PartialEqAsRefStr, PartialOrdAsRefStr, StringEnum},
         EventId, RoomId,
     };
@@ -37,6 +38,15 @@ pub mod v3 {
             /// The event ID to acknowledge up to.
             #[ruma_api(path)]
             pub event_id: &'a EventId,
+
+            /// The thread this receipt applies to.
+            ///
+            /// *Note* that this must be the default value if used with
+            /// [`ReceiptType::FullyRead`].
+            ///
+            /// Defaults to [`ReceiptThread::Unthreaded`].
+            #[serde(rename = "thread_id", skip_serializing_if = "ruma_common::serde::is_default")]
+            pub thread: ReceiptThread,
         }
 
         #[derive(Default)]
@@ -48,7 +58,7 @@ pub mod v3 {
     impl<'a> Request<'a> {
         /// Creates a new `Request` with the given room ID, receipt type and event ID.
         pub fn new(room_id: &'a RoomId, receipt_type: ReceiptType, event_id: &'a EventId) -> Self {
-            Self { room_id, receipt_type, event_id }
+            Self { room_id, receipt_type, event_id, thread: ReceiptThread::default() }
         }
     }