diff --git a/libc/include/bits/threads_inlines.h b/libc/include/bits/threads_inlines.h
index 05b785a..ab294c1 100644
--- a/libc/include/bits/threads_inlines.h
+++ b/libc/include/bits/threads_inlines.h
@@ -28,6 +28,8 @@
 
 #pragma once
 
+#include <sys/cdefs.h>
+
 #include <threads.h>
 
 #include <errno.h>