diff --git a/components/mqtt/Kconfig b/components/mqtt/Kconfig
index 4db6e15..113bac7 100644
--- a/components/mqtt/Kconfig
+++ b/components/mqtt/Kconfig
@@ -124,6 +124,13 @@ menu "ESP-MQTT Configurations"
         help
             MQTT task priority. Higher number denotes higher priority.
 
+    config MQTT_EVENT_QUEUE_SIZE
+        int "Number of queued events."
+        default 1
+        depends on MQTT_USE_CUSTOM_CONFIG
+        help
+            A value higher than 1 enables multiple queued events.
+
     config MQTT_TASK_CORE_SELECTION_ENABLED
         bool "Enable MQTT task core selection"
         help
diff --git a/components/mqtt/host_test/CMakeLists.txt b/components/mqtt/host_test/CMakeLists.txt
index d1c1ac6..db98733 100644
--- a/components/mqtt/host_test/CMakeLists.txt
+++ b/components/mqtt/host_test/CMakeLists.txt
@@ -3,6 +3,7 @@ cmake_minimum_required(VERSION 3.16)
 include($ENV{IDF_PATH}/tools/cmake/project.cmake)
 set(COMPONENTS main)
 list(APPEND EXTRA_COMPONENT_DIRS
+                                 "mocks/heap/"
                                  "$ENV{IDF_PATH}/tools/mocks/esp_hw_support/"
                                  "$ENV{IDF_PATH}/tools/mocks/freertos/"
                                  "$ENV{IDF_PATH}/tools/mocks/esp_timer/"
diff --git a/components/mqtt/host_test/mocks/heap/CMakeLists.txt b/components/mqtt/host_test/mocks/heap/CMakeLists.txt
new file mode 100644
index 0000000..0a0c8a6
--- /dev/null
+++ b/components/mqtt/host_test/mocks/heap/CMakeLists.txt
@@ -0,0 +1,4 @@
+idf_component_get_property(original_heap_dir heap COMPONENT_OVERRIDEN_DIR)
+
+idf_component_register(SRCS heap_mock.c
+  INCLUDE_DIRS "${original_heap_dir}/include")
diff --git a/components/mqtt/host_test/mocks/heap/heap_mock.c b/components/mqtt/host_test/mocks/heap/heap_mock.c
new file mode 100644
index 0000000..e0fc666
--- /dev/null
+++ b/components/mqtt/host_test/mocks/heap/heap_mock.c
@@ -0,0 +1,16 @@
+/*
+ * SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#include "esp_heap_caps.h"
+#include <stdint.h>
+#include <stdlib.h>
+
+
+
+void *heap_caps_calloc(size_t n, size_t size, uint32_t caps) {
+  (void)caps;
+  return calloc(n, size);
+
+}