diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 46c8509..0f6602d 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -93,7 +93,7 @@ build_and_test_qemu:
   script:
     - cit_add_ssh_key "${GITLAB_KEY}"
     - git clone "${IDF_REPO}"
-    - $MQTT_PATH/ci/set_idf.sh master
+    - $MQTT_PATH/ci/set_idf.sh release/v4.1
     - cd $IDF_PATH && tools/idf_tools.py --non-interactive install && eval "$(tools/idf_tools.py --non-interactive export)"
     - $MQTT_PATH/ci/set_mqtt.sh $CI_COMMIT_SHA
     # build publish stress test
diff --git a/mqtt_client.c b/mqtt_client.c
index b50a112..fba72e3 100644
--- a/mqtt_client.c
+++ b/mqtt_client.c
@@ -1460,6 +1460,7 @@ int esp_mqtt_client_subscribe(esp_mqtt_client_handle_t client, const char *topic
                                           &client->mqtt_state.pending_msg_id);
     if (client->mqtt_state.outbound_message->length == 0) {
         ESP_LOGE(TAG, "Subscribe message cannot be created");
+        MQTT_API_UNLOCK(client);
         return -1;
     }
 
@@ -1491,6 +1492,7 @@ int esp_mqtt_client_unsubscribe(esp_mqtt_client_handle_t client, const char *top
                                           topic,
                                           &client->mqtt_state.pending_msg_id);
     if (client->mqtt_state.outbound_message->length == 0) {
+        MQTT_API_UNLOCK(client);
         ESP_LOGE(TAG, "Unubscribe message cannot be created");
         return -1;
     }