diff --git a/libraries/AP_HAL_Linux/Scheduler.cpp b/libraries/AP_HAL_Linux/Scheduler.cpp
index f242745882..ddf57bbb58 100644
--- a/libraries/AP_HAL_Linux/Scheduler.cpp
+++ b/libraries/AP_HAL_Linux/Scheduler.cpp
@@ -83,6 +83,8 @@ void Scheduler::init()
         SCHED_THREAD(io, IO),
     };
 
+    _main_ctx = pthread_self();
+
 #if !APM_BUILD_TYPE(APM_BUILD_Replay)
     // we don't run Replay in real-time...
     mlockall(MCL_CURRENT|MCL_FUTURE);
diff --git a/libraries/AP_HAL_Linux/Scheduler.h b/libraries/AP_HAL_Linux/Scheduler.h
index 4085743bc9..9852e626a9 100644
--- a/libraries/AP_HAL_Linux/Scheduler.h
+++ b/libraries/AP_HAL_Linux/Scheduler.h
@@ -114,9 +114,11 @@ private:
 
     uint64_t _stopped_clock_usec;
     uint64_t _last_stack_debug_msec;
+    pthread_t _main_ctx;
 
     Semaphore _timer_semaphore;
     Semaphore _io_semaphore;
 };
 
 }
+