diff --git a/src/nyancat.c b/src/nyancat.c
index d02b08c..e2c4922 100644
--- a/src/nyancat.c
+++ b/src/nyancat.c
@@ -52,6 +52,7 @@
 #define _XOPEN_SOURCE 500
 #define _DARWIN_C_SOURCE 1
 #define _BSD_SOURCE
+#define _DEFAULT_SOURCE
 #define __BSD_VISIBLE 1
 #include <ctype.h>
 #include <stdio.h>