diff --git a/jtag/src/lib/fclock.c b/jtag/src/lib/fclock.c
index 88b8daba..a2723575 100644
--- a/jtag/src/lib/fclock.c
+++ b/jtag/src/lib/fclock.c
@@ -21,7 +21,7 @@
  */
 
 #define _ISOC99_SOURCE
-#define _POSIX_C_SOURCE 199309L
+#define _POSIX_C_SOURCE 200112L
 #include <unistd.h>
 #include <stdlib.h>
 #include <stdio.h>