diff --git a/crates/xenia-app/tests/golden/sylpheed_n50m.json b/crates/xenia-app/tests/golden/sylpheed_n50m.json
index 066a518..552dc43 100644
--- a/crates/xenia-app/tests/golden/sylpheed_n50m.json
+++ b/crates/xenia-app/tests/golden/sylpheed_n50m.json
@@ -1,6 +1,6 @@
 {
-  "instructions": 50000000,
-  "imports": 339766,
+  "instructions": 50000003,
+  "imports": 451508,
   "unimpl": 0,
   "draws": 0,
   "swaps": 2,
diff --git a/crates/xenia-kernel/src/state.rs b/crates/xenia-kernel/src/state.rs
index 0d6c8cb..0f427ae 100644
--- a/crates/xenia-kernel/src/state.rs
+++ b/crates/xenia-kernel/src/state.rs
@@ -17,6 +17,16 @@ impl PcrWriter for GuestMemoryPcr<'_> {
         // `GuestMemory::write_u32` takes `&self` post-M2 trait flip; the
         // wrapping `&'a GuestMemory` is sufficient.
         self.0.write_u32(pcr_base + 0x2C, hw_id as u32);
+        // PRCB.current_cpu byte at PCR+0x10C (prcb_data@0x100 + current_cpu@0xC).
+        // Canary writes `GetFakeCpuNumber(affinity)` here (xthread.cc:847
+        // `pcr->prcb_data.current_cpu = cpu_index`), which equals the HW thread
+        // id we already compute. Guest spin-barriers (e.g. sub_824D1328, used by
+        // the audio/update pump threads at entries 0x824D2878/0x824D2940) index a
+        // per-HW-thread occupancy array by `lbz r11, 268(r13)` = this byte. Left
+        // unwritten it stayed 0 for every thread, so all threads collided on
+        // slot 0 and the multi-thread rendezvous signature never assembled —
+        // the pump threads spun forever and never fired their KeSetEvent loops.
+        self.0.write_u8(pcr_base + 0x10C, hw_id);
     }
 }
 
diff --git a/crates/xenia-kernel/src/thread.rs b/crates/xenia-kernel/src/thread.rs
index 9f4bc53..96cc09b 100644
--- a/crates/xenia-kernel/src/thread.rs
+++ b/crates/xenia-kernel/src/thread.rs
@@ -57,6 +57,11 @@ pub fn allocate_thread_image(
     mem.write_u32(pcr_base, tls_base);
     mem.write_u32(pcr_base + 0x2C, hw_thread_id as u32);
     mem.write_u32(pcr_base + 0x100, 0x1000);
+    // +0x10C  prcb_data.current_cpu — canary `pcr->prcb_data.current_cpu`
+    //         (PRCB@0x100 + current_cpu@0xC). Guest spin-barriers index a
+    //         per-HW-thread slot array by `lbz r11, 268(r13)` = this byte; it
+    //         must equal the HW thread id (== PCR+0x2C). See state.rs PcrWriter.
+    mem.write_u8(pcr_base + 0x10C, hw_thread_id);
     mem.write_u32(pcr_base + 0x150, 0);
 
     Some(ThreadImage {