diff --git a/src/include/lwip/sys.h b/src/include/lwip/sys.h
index 168e465b..6f9a04d2 100644
--- a/src/include/lwip/sys.h
+++ b/src/include/lwip/sys.h
@@ -38,6 +38,7 @@
 #define LWIP_HDR_SYS_H
 
 #include "lwip/opt.h"
+#include "rtos_pub.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ -120,6 +121,8 @@ typedef void (*lwip_thread_fn)(void *arg);
 
 #else /* LWIP_COMPAT_MUTEX */
 
+typedef beken_mutex_t sys_mutex_t;
+
 /**
  * @ingroup sys_mutex
  * Create a new mutex.