diff --git a/src/nyancat.c b/src/nyancat.c
index 5c6e59c..311627f 100644
--- a/src/nyancat.c
+++ b/src/nyancat.c
@@ -50,6 +50,7 @@
  */
 
 #define _XOPEN_SOURCE 500
+#define _DARWIN_C_SOURCE 1
 #include <ctype.h>
 #include <stdio.h>
 #include <stdint.h>