diff --git a/src/dictionary.c b/src/dictionary.c
index 099f422..c2fc846 100644
--- a/src/dictionary.c
+++ b/src/dictionary.c
@@ -30,6 +30,7 @@
  *
  */
 
+#define _POSIX_C_SOURCE 200808
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/types.h>