diff --git a/local/recipes/system/redbear-sessiond/source/src/acpi_watcher.rs b/local/recipes/system/redbear-sessiond/source/src/acpi_watcher.rs
index 3803c52c65..4a3bd67e90 100644
--- a/local/recipes/system/redbear-sessiond/source/src/acpi_watcher.rs
+++ b/local/recipes/system/redbear-sessiond/source/src/acpi_watcher.rs
@@ -3,17 +3,50 @@ use zbus::Connection;
 use crate::runtime_state::SharedRuntime;
 
 #[cfg(target_os = "redox")]
-const KSTOP_PATH: &str = "/scheme/kernel.acpi/kstop";
+mod redox_shutdown {
+    /// Block until the kernel signals a shutdown.
+    ///
+    /// Phase B of the ACPI fork-sync replaced the `/scheme/kernel.acpi/kstop`
+    /// file with a single Fd-based call() interface. The kstop sub-handle
+    /// is event-driven (see kernel/scheme/acpi.rs register_kstop).
+    ///
+    /// Rather than subscribing to the event queue (which would require
+    /// pulling in `redox_event` and dealing with the macro-deprecation
+    /// churn), we poll the `AcpiVerb::CheckShutdown` kcall every 250ms.
+    /// This is the supported pattern for userspace that just wants
+    /// the boolean "is shutdown pending" signal.
+    pub fn wait_for_shutdown_edge() -> std::io::Result<()> {
+        let parent = libredox::Fd::open(
+            "/scheme/kernel.acpi",
+            libredox::flag::O_CLOEXEC,
+            0,
+        )?;
+        // Open the kstop sub-handle. The kernel requires us to call
+        // CheckShutdown on the kstop handle (HandleBits::KSTOP_HANDLE),
+        // not on the parent handle.
+        let kstop = parent.openat("kstop", libredox::flag::O_CLOEXEC, 0)?;
+
+        // AcpiVerb::CheckShutdown = 2.
+        loop {
+            let mut buf = [0u8; 8];
+            let n = kstop.call_ro(
+                &mut buf,
+                redox_syscall::flag::CallFlags::empty(),
+                &[2u64],
+            )?;
+            if n > 0 {
+                let shutdown = u64::from_le_bytes(buf[..8].try_into().unwrap_or([0; 8]));
+                if shutdown != 0 {
+                    return Ok(());
+                }
+            }
+            std::thread::sleep(std::time::Duration::from_millis(250));
+        }
+    }
+}
 
 #[cfg(target_os = "redox")]
-fn wait_for_shutdown_edge() -> std::io::Result<()> {
-    use std::io::Read;
-
-    let mut file = std::fs::File::open(KSTOP_PATH)?;
-    let mut byte = [0_u8; 1];
-    let _ = file.read(&mut byte)?;
-    Ok(())
-}
+use redox_shutdown::wait_for_shutdown_edge;
 
 pub async fn watch_and_emit(connection: Connection, runtime: SharedRuntime) {
     #[cfg(target_os = "redox")]
@@ -45,4 +78,4 @@ pub async fn watch_and_emit(connection: Connection, runtime: SharedRuntime) {
         let _ = connection;
         let _ = runtime;
     }
-}
+}
\ No newline at end of file
diff --git a/local/sources/base b/local/sources/base
index de9d1f495f..8140a2cd27 160000
--- a/local/sources/base
+++ b/local/sources/base
@@ -1 +1 @@
-Subproject commit de9d1f495f0444aeb93e10407e0c76514c9bde14
+Subproject commit 8140a2cd2753d8b85d536068bf4a79b8a5a7e961
diff --git a/local/sources/kernel b/local/sources/kernel
index 4cb9d80396..4f2a0436eb 160000
--- a/local/sources/kernel
+++ b/local/sources/kernel
@@ -1 +1 @@
-Subproject commit 4cb9d80396f727bacff1dc41fefaa2df18197a8b
+Subproject commit 4f2a0436eb98863e400496557fb529d447ff66e2