diff --git a/lib_acl_cpp/src/stream/mbedtls_conf.cpp b/lib_acl_cpp/src/stream/mbedtls_conf.cpp
index dada9abae..f05c05654 100644
--- a/lib_acl_cpp/src/stream/mbedtls_conf.cpp
+++ b/lib_acl_cpp/src/stream/mbedtls_conf.cpp
@@ -31,6 +31,7 @@
 
 # ifdef HAS_MBEDTLS_DLL
 
+#  define THREADING_SET_ALT_NAME	"mbedtls_threading_set_alt"
 #  define PK_INIT_NAME			"mbedtls_pk_init"
 #  define PK_FREE_NAME			"mbedtls_pk_free"
 #  define PK_PARSE_KEYFILE_NAME		"mbedtls_pk_parse_keyfile"
@@ -76,6 +77,11 @@
 
 #  define SSL_SETUP_NAME		"mbedtls_ssl_setup"
 
+typedef void (*threading_set_alt_fn)(
+	void (*init)(mbedtls_threading_mutex_t *),
+	void (*free)(mbedtls_threading_mutex_t *),
+	int (*lock)(mbedtls_threading_mutex_t *),
+	int (*unlock)( mbedtls_threading_mutex_t *));
 typedef void (*pk_init_fn)(PKEY*);
 typedef void (*pk_free_fn)(PKEY*);
 typedef int  (*pk_parse_keyfile_fn)(PKEY*, const char*, const char*);
@@ -127,6 +133,7 @@ typedef int  (*ssl_cache_get_fn)(void*, mbedtls_ssl_session*);
 
 typedef int  (*ssl_setup_fn)(mbedtls_ssl_context*, mbedtls_ssl_config*);
 
+static threading_set_alt_fn		__threading_set_alt;
 static pk_init_fn			__pk_init;
 static pk_free_fn			__pk_free;
 static pk_parse_keyfile_fn		__pk_parse_keyfile;
@@ -250,6 +257,7 @@ extern bool mbedtls_dll_load_io(void); // defined in mbedtls_io.cpp
 
 static bool load_from_crypto(void)
 {
+	LOAD_CRYPTO(THREADING_SET_ALT_NAME, threading_set_alt_fn, __threading_set_alt);
 	LOAD_CRYPTO(PK_INIT_NAME, pk_init_fn, __pk_init);
 	LOAD_CRYPTO(PK_FREE_NAME, pk_free_fn, __pk_free);
 	LOAD_CRYPTO(PK_PARSE_KEYFILE_NAME, pk_parse_keyfile_fn, __pk_parse_keyfile);
@@ -374,6 +382,7 @@ static void mbedtls_dll_load(void)
 
 # else // !HAS_MBEDTLS_DLL && HAS_MBEDTLS
 
+#  define __threading_set_alt		::mbedtls_threading_set_alt
 #  define __pk_init			::mbedtls_pk_init
 #  define __pk_free			::mbedtls_pk_free
 #  define __pk_parse_keyfile		::mbedtls_pk_parse_keyfile
@@ -519,6 +528,30 @@ static void my_debug( void *ctx, int level, const char* fname, int line,
 #define CONF_INIT_OK	1
 #define CONF_INIT_ERR	2
 
+static void mutex_init(mbedtls_threading_mutex_t* mutex)
+{
+	acl_pthread_mutex_t* m = (acl_pthread_mutex_t*) mutex;
+	acl_pthread_mutex_init(m, NULL);
+}
+
+static void mutex_free(mbedtls_threading_mutex_t* mutex)
+{
+	acl_pthread_mutex_t* m = (acl_pthread_mutex_t*) mutex;
+	acl_pthread_mutex_destroy(m);
+}
+
+static int mutex_lock(mbedtls_threading_mutex_t* mutex)
+{
+	acl_pthread_mutex_t* m = (acl_pthread_mutex_t*) mutex;
+	return acl_pthread_mutex_lock(m);
+}
+
+static int mutex_unlock(mbedtls_threading_mutex_t* mutex)
+{
+	acl_pthread_mutex_t* m = (acl_pthread_mutex_t*) mutex;
+	return acl_pthread_mutex_unlock(m);
+}
+
 bool mbedtls_conf::init_once(void)
 {
 	if (!load()) {
@@ -532,6 +565,8 @@ bool mbedtls_conf::init_once(void)
 		return false;
 	}
 
+	__threading_set_alt(mutex_init, mutex_free, mutex_lock, mutex_unlock);
+
 #ifdef HAS_MBEDTLS
 	__ssl_config_init((mbedtls_ssl_config*) conf_);
 	__entropy_init((mbedtls_entropy_context*) entropy_);