diff --git a/components/pthread/pthread.c b/components/pthread/pthread.c
index 73f23a00d..7817355fb 100644
--- a/components/pthread/pthread.c
+++ b/components/pthread/pthread.c
@@ -72,7 +72,7 @@ static int IRAM_ATTR pthread_mutex_lock_internal(esp_pthread_mutex_t *mux, TickT
 esp_err_t esp_pthread_init(void)
 {
     vListInitialise((List_t *)&s_threads_list);
-    s_once_mux = xSemaphoreCreateMutex();
+    s_once_mux = xSemaphoreCreateRecursiveMutex();
     if (s_once_mux == NULL) {
         return ESP_ERR_NO_MEM;
     }
@@ -232,6 +232,7 @@ int pthread_join(pthread_t thread, void **retval)
 {
     esp_pthread_t *pthread = (esp_pthread_t *)thread;
     int ret = 0;
+    bool wait = false;
 
     ESP_LOGV(TAG, "%s %p", __FUNCTION__, pthread);
 
@@ -257,6 +258,7 @@ int pthread_join(pthread_t thread, void **retval)
         } else {
             if (pthread->state == PTHREAD_TASK_STATE_RUN) {
                 pthread->join_task = xTaskGetCurrentTaskHandle();
+                wait = true;
             } else {
                 pthread_delete(pthread);
             }
@@ -264,7 +266,7 @@ int pthread_join(pthread_t thread, void **retval)
     }
     xSemaphoreGive(s_threads_mux);
 
-    if (ret == 0 && pthread->join_task) {
+    if (ret == 0 && wait) {
         xTaskNotifyWait(0, 0, NULL, portMAX_DELAY);
         if (xSemaphoreTake(s_threads_mux, portMAX_DELAY) != pdTRUE) {
             assert(false && "Failed to lock threads list!");
@@ -375,7 +377,9 @@ int pthread_once(pthread_once_t *once_control, void (*init_routine)(void))
     TaskHandle_t cur_task = xTaskGetCurrentTaskHandle();
     // do not take mutex if OS is not running yet
     if (xTaskGetSchedulerState() == taskSCHEDULER_NOT_STARTED ||
-            !cur_task || xSemaphoreTake(s_once_mux, portMAX_DELAY) == pdTRUE)
+            // init_routine can call pthread_once for another objects, so use recursive mutex
+            // FIXME: behaviour is undefined if init_routine calls pthread_once for the same object in the current context
+            !cur_task || xSemaphoreTakeRecursive(s_once_mux, portMAX_DELAY) == pdTRUE)
     {
         if (!once_control->init_executed) {
             ESP_LOGV(TAG, "%s: call init_routine %p", __FUNCTION__, once_control);
@@ -383,7 +387,7 @@ int pthread_once(pthread_once_t *once_control, void (*init_routine)(void))
             once_control->init_executed = 1;
         }
         if (cur_task) {
-            xSemaphoreGive(s_once_mux);
+            xSemaphoreGiveRecursive(s_once_mux);
         }
     }
     else
diff --git a/components/pthread/test/test_pthread_cxx.cpp b/components/pthread/test/test_pthread_cxx.cpp
index 287a1da1b..ced961d09 100644
--- a/components/pthread/test/test_pthread_cxx.cpp
+++ b/components/pthread/test/test_pthread_cxx.cpp
@@ -1,10 +1,17 @@
 #include <iostream>
+#include <sstream>
 #include <thread>
 #include <mutex>
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
 #include "unity.h"
 
 #if __GTHREADS && __GTHREADS_CXX0X
 
+#define LOG_LOCAL_LEVEL CONFIG_LOG_DEFAULT_LEVEL
+#include "esp_log.h"
+const static char *TAG = "pthread_test";
+
 static std::shared_ptr<int> global_sp;
 static std::mutex           mtx;
 static std::recursive_mutex recur_mtx;
@@ -56,7 +63,7 @@ static void thread_main()
     }
 }
 
-TEST_CASE("pthread CXX", "[pthread]")
+TEST_CASE("pthread C++", "[pthread]")
 {
     global_sp.reset(new int(1));
 
@@ -80,4 +87,36 @@ TEST_CASE("pthread CXX", "[pthread]")
     }
 }
 
+static void task_test_sandbox(void *arg)
+{
+    bool *running = (bool *)arg;
+
+    ESP_LOGI(TAG, "About to create a string stream");
+    std::stringstream ss;
+    ESP_LOGI(TAG, "About to write to string stream");
+    ss << "Hello World!";
+    ESP_LOGI(TAG, "About to extract from stringstream");
+    ESP_LOGI(TAG, "Text: %s", ss.str().c_str());
+
+    if (running) {
+        *running = false;
+        vTaskDelete(NULL);
+    }
+}
+
+TEST_CASE("pthread mix C/C++", "[pthread]")
+{
+    bool running = true;
+
+    std::thread t1(task_test_sandbox, (void *)NULL);
+    xTaskCreatePinnedToCore((TaskFunction_t)&task_test_sandbox, "task_test_sandbox", 2048, &running, 5, NULL, 0);
+    while (running) {
+        vTaskDelay(1);
+    }
+    if (t1.joinable()) {
+        std::cout << "Join thread " << std::hex << t1.get_id() << std::endl;
+        t1.join();
+    }
+}
+
 #endif