diff --git a/crates/windows-ioring-sys/src/completion_wake.rs b/crates/windows-ioring-sys/src/completion_wake.rs
index 75adc57bb..d9f2e7d34 100644
--- a/crates/windows-ioring-sys/src/completion_wake.rs
+++ b/crates/windows-ioring-sys/src/completion_wake.rs
@@ -57,7 +57,10 @@ impl CompletionWake {
     /// (`M4.2`, `M26.9`, `M26.12`).
     ///
     /// `env` binds the wait's pool -- to a NUMA node's, for instance; `None` is the process's
-    /// default pool.
+    /// default pool. It is [`windows_threadpool_sys::callback_env::CallbackEnviron`], the type of
+    /// the `windows-threadpool-sys` this crate depends on: another version of that crate has
+    /// another `CallbackEnviron`, so a caller builds the environment with the version this crate
+    /// resolves to.
     ///
     /// # Errors
     ///
diff --git a/crates/windows-ioring-sys/src/event_delivery.rs b/crates/windows-ioring-sys/src/event_delivery.rs
index 5d99c488d..2b54a0008 100644
--- a/crates/windows-ioring-sys/src/event_delivery.rs
+++ b/crates/windows-ioring-sys/src/event_delivery.rs
@@ -148,6 +148,11 @@ impl<T: Send + 'static, X: Send + 'static> EventDelivery<T, X> {
     /// Neither makes the ring a synchronization provider: its lock is its
     /// own, and a callback holds it only for as long as a scope it opens.
     ///
+    /// `env` is [`windows_threadpool_sys::callback_env::CallbackEnviron`], the
+    /// type of the `windows-threadpool-sys` this crate depends on. Another
+    /// version of that crate has another `CallbackEnviron`, so a caller builds
+    /// the environment with the version this crate resolves to.
+    ///
     /// # Errors
     ///
     /// Returns [`io::ErrorKind::Unsupported`] if the running system does not