diff --git a/extensions/assets-manager/AssetsManager.cpp b/extensions/assets-manager/AssetsManager.cpp
index 2ebc2d449d69..5920f53dfd43 100644
--- a/extensions/assets-manager/AssetsManager.cpp
+++ b/extensions/assets-manager/AssetsManager.cpp
@@ -220,7 +220,7 @@ void AssetsManager::createDirectory(const std::string& path)
 
     // Create path recursively
     subpath = "";
-    for (int i = 0; i < dirs.size(); i++) {
+    for (int i = 0; i < dirs.size(); ++i) {
         subpath += dirs[i];
         dir = opendir (subpath.c_str());
         if (!dir)
@@ -441,7 +441,7 @@ void AssetsManager::startUpdate()
             _downloadUnits.clear();
             _totalWaitToDownload = _totalToDownload = 0;
             std::string packageUrl = _remoteManifest->getPackageUrl();
-            for (auto it = diff_map.begin(); it != diff_map.end(); it++) {
+            for (auto it = diff_map.begin(); it != diff_map.end(); ++it) {
                 Manifest::AssetDiff diff = it->second;
 
                 if (diff.type == Manifest::DiffType::DELETED) {
@@ -568,7 +568,7 @@ void AssetsManager::update()
 
 void AssetsManager::batchDownload(const std::unordered_map<std::string, Downloader::DownloadUnit> &units)
 {
-    for (auto it = units.cbegin(); it != units.cend(); it++) {
+    for (auto it = units.cbegin(); it != units.cend(); ++it) {
         Downloader::DownloadUnit unit = it->second;
         std::string srcUrl = unit.srcUrl;
         std::string storagePath = unit.storagePath;
diff --git a/extensions/assets-manager/Downloader.cpp b/extensions/assets-manager/Downloader.cpp
index 2f494edf2a2c..324f4692329f 100644
--- a/extensions/assets-manager/Downloader.cpp
+++ b/extensions/assets-manager/Downloader.cpp
@@ -23,7 +23,6 @@
  ****************************************************************************/
 
 #include "Downloader.h"
-#include "base/threadpool.hpp"
 
 #include <curl/curl.h>
 #include <curl/easy.h>
@@ -39,6 +38,10 @@ NS_CC_EXT_BEGIN
 #define LOW_SPEED_LIMIT     1L
 #define LOW_SPEED_TIME      5L
 
+#if USE_THREAD_POOL
+#include "base/threadpool.hpp"
+#endif
+
 #define POOL() static_cast<threadpool::pool*>(this->_threadPool)
 
 static size_t curlWriteFunc(void *ptr, size_t size, size_t nmemb, void *userdata)
@@ -186,7 +189,7 @@ void Downloader::downloadSync(const std::string &srcUrl, const std::string &stor
 
 void Downloader::batchDownload(const std::unordered_map<std::string, Downloader::DownloadUnit> &units)
 {
-    for (auto it = units.cbegin(); it != units.cend(); it++) {
+    for (auto it = units.cbegin(); it != units.cend(); ++it) {
         DownloadUnit unit = it->second;
         std::string srcUrl = unit.srcUrl;
         std::string storagePath = unit.storagePath;
diff --git a/extensions/assets-manager/Manifest.cpp b/extensions/assets-manager/Manifest.cpp
index c5ab46e70f3d..33c1d6758d98 100644
--- a/extensions/assets-manager/Manifest.cpp
+++ b/extensions/assets-manager/Manifest.cpp
@@ -125,7 +125,7 @@ bool Manifest::versionEquals(const Manifest *b) const
             return false;
         
         // Check groups version
-        for (int i = 0; i < _groups.size(); i++) {
+        for (int i = 0; i < _groups.size(); ++i) {
             std::string gid =_groups[i];
             // Check group name
             if (gid != bGroups[i])
@@ -147,7 +147,7 @@ std::unordered_map<std::string, Manifest::AssetDiff> Manifest::genDiff(const Man
     Asset valueA;
     Asset valueB;
     std::unordered_map<std::string, Asset>::const_iterator valueIt, it;
-    for (it = _assets.begin(); it != _assets.end(); it++)
+    for (it = _assets.begin(); it != _assets.end(); ++it)
     {
         key = it->first;
         valueA = it->second;
@@ -172,7 +172,7 @@ std::unordered_map<std::string, Manifest::AssetDiff> Manifest::genDiff(const Man
         }
     }
     
-    for (it = bAssets.begin(); it != bAssets.end(); it++)
+    for (it = bAssets.begin(); it != bAssets.end(); ++it)
     {
         key = it->first;
         valueB = it->second;
@@ -385,7 +385,7 @@ void Manifest::loadManifest(const rapidjson::Document &json)
         const rapidjson::Value& paths = json[KEY_SEARCH_PATHS];
         if (paths.IsArray())
         {
-            for (rapidjson::SizeType i = 0; i < paths.Size(); i++)
+            for (rapidjson::SizeType i = 0; i < paths.Size(); ++i)
             {
                 if (paths[i].IsString()) {
                     _searchPaths.push_back(paths[i].GetString());