diff --git a/crates/xenia-app/src/main.rs b/crates/xenia-app/src/main.rs
index 420c64f..eb7849a 100644
--- a/crates/xenia-app/src/main.rs
+++ b/crates/xenia-app/src/main.rs
@@ -1031,7 +1031,15 @@ fn cmd_exec_inner(
             let v = v.trim().to_ascii_lowercase();
             v == "1" || v == "true" || v == "yes"
         });
-    let parallel_active = parallel || parallel_via_env;
+    // iterate-4E: native-threads mode is a superset of parallel behavior (it
+    // delegates to the free-run executor and runs guest code on multiple host
+    // threads concurrently). Folding it into `parallel_active` is what enables
+    // the host-atomic ReservationTable below — MANDATORY under concurrency, else
+    // lwarx/stwcx on non-primary slots silently can't observe cross-thread
+    // stores (PPCBUG-108). Also flips `kernel.parallel_active` so the wall-clock
+    // vsync/coordination paths engage like `--parallel`.
+    let native_active = native_threads_enabled();
+    let parallel_active = parallel || parallel_via_env || native_active;
     kernel.parallel_active = parallel_active;
     // AUDIT-032: default is `KernelState::xaudio_tick_enabled = true` now
     // that the dedicated worker eliminates HW-thread hijack regressions.