diff --git a/wolfssh/port.h b/wolfssh/port.h
index ef21ecc..8b4fc66 100644
--- a/wolfssh/port.h
+++ b/wolfssh/port.h
@@ -1099,6 +1099,7 @@ extern "C" {
 #elif defined(FREESCALE_MQX)
     /* MQX does not have FIONREAD, use SO_RCVNUM with getsockopt() instead */
     #include <ioctl.h>
+    #include <rtcs.h>
     #define WFIONREAD SO_RCVNUM
     static inline void ws_Ioctl(int fd, int flag, int* ret)
     {