diff --git a/cpu/native/net/tap.c b/cpu/native/net/tap.c
index ab734ea686..99edc4368f 100644
--- a/cpu/native/net/tap.c
+++ b/cpu/native/net/tap.c
@@ -149,7 +149,7 @@ void _native_handle_tap_input(void)
 }
 
 #ifdef __MACH__
-void sigio_child()
+void sigio_child(void)
 {
     pid_t parent = _native_pid;
 
diff --git a/sys/posix/include/unistd.h b/sys/posix/include/unistd.h
index 25b23ba799..987802627e 100644
--- a/sys/posix/include/unistd.h
+++ b/sys/posix/include/unistd.h
@@ -52,9 +52,13 @@
 int close(int fildes);
 
 #ifndef __USECONDS_T_TYPE
+#ifndef __MACH__
 typedef unsigned long __USECONDS_T_TYPE;
-#endif
 typedef __USECONDS_T_TYPE __useconds_t;
+#else
+typedef __darwin_useconds_t __useconds_t;
+#endif
+#endif
 typedef __useconds_t useconds_t;
 
 /**