diff --git a/lib/unix/wait.c b/lib/unix/wait.c
index 1ddf60e..fc2f520 100644
--- a/lib/unix/wait.c
+++ b/lib/unix/wait.c
@@ -28,10 +28,6 @@
  * THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE.
  */
 
-#ifdef __MACH__
-#  define _POSIX_SOURCE
-#endif
-
 #include "unix.h"
 
 #include <string.h>