diff --git a/system/include/emscripten/threading.h b/system/include/emscripten/threading.h
index aaf02b0b2bb23..fee6348f64733 100644
--- a/system/include/emscripten/threading.h
+++ b/system/include/emscripten/threading.h
@@ -310,6 +310,14 @@ int emscripten_sync_run_in_main_runtime_thread_(EM_FUNC_SIGNATURE sig, void *fun
 //  - Note that multiple asynchronous commands from a single pthread/Worker are
 //    guaranteed to be executed on the main thread in the program order they
 //    were called in.
+//  - Note that synchronous and asynchronous commands are *also* guaranteed to
+//    be executed in order. That is, all commands, sync and async, will not get
+//    reordered in the queue, but will be executed in the sequential order in
+//    which they were dispatched. If you issue commands A, B, C, then regardless
+//    of which of them are sync or async, they will execute in that same order
+//    on the main runtime thread. The only difference between an async and a
+//    sync command is that an async one has no return value, and does not block
+//    the calling thread.
 void emscripten_async_run_in_main_runtime_thread_(EM_FUNC_SIGNATURE sig, void *func_ptr, ...);
 
 // The 'async_waitable' variant of the run_in_main_runtime_thread functions run