diff --git a/src/thread/thread.c b/src/thread/thread.c
index 56871a0..0163107 100644
--- a/src/thread/thread.c
+++ b/src/thread/thread.c
@@ -319,6 +319,7 @@ void __attribute__((constructor)) setup_main_thread()
     main->status = 0;
     main->retvalue = NULL;
     main->last_waited = NULL;
+    main->mutex_fifo_entry = NULL;
     running = main;
 
     // Create a context with static stack to clean everything at the end.