diff --git a/testing/ostest/mqueue.c b/testing/ostest/mqueue.c
index 586fa8e0b..68938ce82 100644
--- a/testing/ostest/mqueue.c
+++ b/testing/ostest/mqueue.c
@@ -359,7 +359,7 @@ void mqueue_test(void)
   /* Wake up the receiver thread with a signal */
 
   printf("mqueue_test: Killing receiver\n");
-  pthread_kill(receiver, 9);
+  pthread_kill(receiver, SIGUSR1);
 
   /* Wait a bit to see if the thread exits on its own */