diff --git a/tokio/CHANGELOG.md b/tokio/CHANGELOG.md
index 42d1f6b8f2a..60266e42b35 100644
--- a/tokio/CHANGELOG.md
+++ b/tokio/CHANGELOG.md
@@ -134,6 +134,14 @@ This release fixes a bug in `Notified::enable`. ([#4747])
 [#4729]: https://github.com/tokio-rs/tokio/pull/4729
 [#4739]: https://github.com/tokio-rs/tokio/pull/4739
 
+# 1.18.5 (January 17, 2023)
+
+### Fixed
+
+- io: fix unsoundness in `ReadHalf::unsplit` ([#5375])
+
+[#5375]: https://github.com/tokio-rs/tokio/pull/5375
+
 # 1.18.4 (January 3, 2022)
 
 ### Fixed
@@ -270,7 +278,7 @@ performance improvements.
 - time: use bit manipulation instead of modulo to improve performance ([#4480])
 - net: use `std::future::Ready` instead of our own `Ready` future ([#4271])
 - replace deprecated `atomic::spin_loop_hint` with `hint::spin_loop` ([#4491])
-- fix miri failures in intrusive linked lists ([#4397]) 
+- fix miri failures in intrusive linked lists ([#4397])
 
 ### Documented
 
diff --git a/tokio/src/io/split.rs b/tokio/src/io/split.rs
index 2e0da95665f..f067b65a826 100644
--- a/tokio/src/io/split.rs
+++ b/tokio/src/io/split.rs
@@ -75,7 +75,10 @@ impl<T> ReadHalf<T> {
     /// This can be checked ahead of time by comparing the stream ID
     /// of the two halves.
     #[track_caller]
-    pub fn unsplit(self, wr: WriteHalf<T>) -> T {
+    pub fn unsplit(self, wr: WriteHalf<T>) -> T
+    where
+        T: Unpin,
+    {
         if self.is_pair_of(&wr) {
             drop(wr);