diff --git a/src/pass.c b/src/pass.c
index 7526fd2..3bf6fc4 100644
--- a/src/pass.c
+++ b/src/pass.c
@@ -20,6 +20,7 @@
  *
  */
 
+#define _POSIX_C_SOURCE 200809L
 
 #include <stdint.h>
 #include "nwipe.h"