diff --git a/main.c b/main.c
index 5959f0c..b8116b0 100644
--- a/main.c
+++ b/main.c
@@ -16,6 +16,8 @@
  * <https://www.gnu.org/licenses/>.
  */
 
+#define _POSIX_SOURCE
+
 #include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>