diff --git a/lib/plat/freertos/private-lib-plat-freertos.h b/lib/plat/freertos/private-lib-plat-freertos.h
index 052f43ad5..f8d61499c 100644
--- a/lib/plat/freertos/private-lib-plat-freertos.h
+++ b/lib/plat/freertos/private-lib-plat-freertos.h
@@ -72,6 +72,12 @@ gai_strerror(int);
 #include <errno.h>
 #endif
 
+typedef SemaphoreHandle_t lws_mutex_t;
+#define lws_mutex_init(x)	x = xSemaphoreCreateMutex()
+#define lws_mutex_destroy(x)	vSemaphoreDelete(x)
+#define lws_mutex_lock(x)	xSemaphoreTake(x, portMAX_DELAY)
+#define lws_mutex_unlock(x)	xSemaphoreGive(x)
+
 #include <lwip/sockets.h>
 
  #if defined(LWS_BUILTIN_GETIFADDRS)
diff --git a/lib/plat/unix/private-lib-plat-unix.h b/lib/plat/unix/private-lib-plat-unix.h
index d64f89883..feb222739 100644
--- a/lib/plat/unix/private-lib-plat-unix.h
+++ b/lib/plat/unix/private-lib-plat-unix.h
@@ -75,6 +75,15 @@
 	#endif
 #endif
 
+#if defined(LWS_HAVE_PTHREAD_H)
+#include <pthread.h>
+typedef pthread_mutex_t lws_mutex_t;
+#define lws_mutex_init(x)	pthread_mutex_init(&(x), NULL)
+#define lws_mutex_destroy(x)	pthread_mutex_destroy(&(x))
+#define lws_mutex_lock(x)	pthread_mutex_lock(&(x))
+#define lws_mutex_unlock(x)	pthread_mutex_unlock(&(x))
+#endif
+
 #if defined(__sun) && defined(__GNUC__)
 
 #include <arpa/nameser_compat.h>
diff --git a/lib/plat/windows/private-lib-plat-windows.h b/lib/plat/windows/private-lib-plat-windows.h
index 03cffd175..56bfc3c00 100644
--- a/lib/plat/windows/private-lib-plat-windows.h
+++ b/lib/plat/windows/private-lib-plat-windows.h
@@ -66,6 +66,15 @@
 
 #if defined(LWS_WITH_UNIX_SOCK)
 #include <afunix.h>
+#endif
+
+#if defined(LWS_HAVE_PTHREAD_H)
+#include <pthread.h>
+typedef pthread_mutex_t lws_mutex_t;
+#define lws_mutex_init(x)	pthread_mutex_init(&(x), NULL)
+#define lws_mutex_destroy(x)	pthread_mutex_destroy(&(x))
+#define lws_mutex_lock(x)	pthread_mutex_lock(&(x))
+#define lws_mutex_unlock(x)	pthread_mutex_unlock(&(x))
 #endif
 
  #if !defined(LWS_HAVE_ATOLL)