diff --git a/src/drivers/device/vdev_posix.cpp b/src/drivers/device/vdev_posix.cpp
index 354b5cdd20..509f247956 100644
--- a/src/drivers/device/vdev_posix.cpp
+++ b/src/drivers/device/vdev_posix.cpp
@@ -55,7 +55,7 @@ using namespace device;
 pthread_mutex_t filemutex = PTHREAD_MUTEX_INITIALIZER;
 px4_sem_t lockstep_sem;
 bool sim_lockstep = false;
-bool sim_delay = false;
+volatile bool sim_delay = false;
 
 extern "C" {
 
diff --git a/src/platforms/posix/main.cpp b/src/platforms/posix/main.cpp
index cce995afd9..3a66b60a76 100644
--- a/src/platforms/posix/main.cpp
+++ b/src/platforms/posix/main.cpp
@@ -71,7 +71,7 @@ const unsigned path_max_len = PATH_MAX;
 const unsigned path_max_len = 1024;
 #endif
 
-static bool _ExitFlag = false;
+static volatile bool _ExitFlag = false;
 
 static struct termios orig_term;