diff --git a/testing/misc_tools.c b/testing/misc_tools.c
index f039740d..af6f6872 100644
--- a/testing/misc_tools.c
+++ b/testing/misc_tools.c
@@ -27,7 +27,7 @@
 
 #ifndef _POSIX_C_SOURCE
 // For nanosleep().
-#define _POSIX_C_SOURCE 199309L
+#define _POSIX_C_SOURCE 200112L
 #endif
 
 #include "misc_tools.h"