diff --git a/src/main/cpp/aprinitializer.cpp b/src/main/cpp/aprinitializer.cpp
index 732924188..ce53a5d6f 100644
--- a/src/main/cpp/aprinitializer.cpp
+++ b/src/main/cpp/aprinitializer.cpp
@@ -140,7 +140,7 @@ void APRInitializer::addObject(size_t key, const ObjectPtr& pObject)
 		m_priv->objects.emplace_back(key, pObject);
 }
 
-const ObjectPtr& APRInitializer::findOrAddObject(size_t key, std::function<ObjectPtr()> creator)
+const ObjectPtr APRInitializer::findOrAddObject(size_t key, std::function<ObjectPtr()> creator)
 {
 	std::lock_guard<std::mutex> lock(m_priv->mutex);
 	if (m_priv->objects.empty())
diff --git a/src/main/cpp/domconfigurator.cpp b/src/main/cpp/domconfigurator.cpp
index 04424ec3e..e735986e0 100644
--- a/src/main/cpp/domconfigurator.cpp
+++ b/src/main/cpp/domconfigurator.cpp
@@ -144,7 +144,7 @@ class XMLWatchdog  : public FileWatchdog
 		Call DOMConfigurator#doConfigure with the
 		<code>filename</code> to reconfigure log4cxx.
 		*/
-		void doOnChange()
+		void doOnChange() override
 		{
 			DOMConfigurator().doConfigure(file(),
 				LogManager::getLoggerRepository());
diff --git a/src/main/cpp/filewatchdog.cpp b/src/main/cpp/filewatchdog.cpp
index 66c7a482b..a7e72d324 100644
--- a/src/main/cpp/filewatchdog.cpp
+++ b/src/main/cpp/filewatchdog.cpp
@@ -53,6 +53,12 @@ struct FileWatchdog::FileWatchdogPrivate{
 	bool warnedAlready;
 	LogString taskName;
 	ThreadUtility::ManagerWeakPtr taskManager;
+
+	/**
+	Serialize access and modification to: file, lastModif and warnedAlready.
+	Recursive because doOnChange may re-enter watchdog methods.
+	*/
+	std::recursive_mutex mutex;
 };
 
 FileWatchdog::FileWatchdog(const File& file1)
@@ -95,6 +101,7 @@ const File& FileWatchdog::file()
 
 void FileWatchdog::checkAndConfigure()
 {
+	std::lock_guard<std::recursive_mutex> lock(m_priv->mutex);
 	if (LogLog::isDebugEnabled())
 	{
 		LogString msg(LOG4CXX_STR("Checking ["));
@@ -164,6 +171,7 @@ void FileWatchdog::setDelay(long delay1){
 
 void FileWatchdog::setFile(const File& newValue)
 {
+	std::lock_guard<std::recursive_mutex> lock(m_priv->mutex);
 	if (m_priv->file.getPath() != newValue.getPath())
 	{
 		m_priv->file = newValue;
diff --git a/src/main/cpp/propertyconfigurator.cpp b/src/main/cpp/propertyconfigurator.cpp
index 2cd865987..578630657 100644
--- a/src/main/cpp/propertyconfigurator.cpp
+++ b/src/main/cpp/propertyconfigurator.cpp
@@ -60,7 +60,7 @@ class PropertyWatchdog  : public FileWatchdog
 		const spi::LoggerRepositoryPtr& hierarchy) with the
 		<code>filename</code> to reconfigure log4cxx.
 		*/
-		void doOnChange()
+		void doOnChange() override
 		{
 			PropertyConfigurator().doConfigure(file(),
 				LogManager::getLoggerRepository());
diff --git a/src/main/cpp/socketappenderskeleton.cpp b/src/main/cpp/socketappenderskeleton.cpp
index 9b13e0617..9f2582f24 100644
--- a/src/main/cpp/socketappenderskeleton.cpp
+++ b/src/main/cpp/socketappenderskeleton.cpp
@@ -235,6 +235,8 @@ void SocketAppenderSkeleton::SocketAppenderSkeletonPriv::setOutputSink(const Soc
 {
 	OutputStreamPtr os = std::make_shared<SocketOutputStream>(socket);
 	auto charset = CharsetEncoder::getUTF8Encoder();
+	// Serialize with AppenderSkeleton::doAppend
+	std::lock_guard<std::recursive_mutex> lock(this->mutex);
 	this->outputSink = std::make_shared<OutputStreamWriter>(os, charset);
 }
 
@@ -244,6 +246,7 @@ void SocketAppenderSkeleton::SocketAppenderSkeletonPriv::close()
 		;
 	else if (auto pManager = this->taskManager.lock())
 		pManager->value().removePeriodicTask(this->taskName);
+	std::lock_guard<std::recursive_mutex> lock(this->mutex);
 	if (this->outputSink)
 	{
 		try
diff --git a/src/main/include/log4cxx/helpers/aprinitializer.h b/src/main/include/log4cxx/helpers/aprinitializer.h
index 9acd90d18..e4dda4a49 100644
--- a/src/main/include/log4cxx/helpers/aprinitializer.h
+++ b/src/main/include/log4cxx/helpers/aprinitializer.h
@@ -66,7 +66,7 @@ class APRInitializer
 		APRInitializer& operator=(const APRInitializer&) = delete;
 	private: // Modifiers
 		void addObject(size_t key, const ObjectPtr& pObject);
-		const ObjectPtr& findOrAddObject(size_t key, std::function<ObjectPtr()> creator);
+		const ObjectPtr findOrAddObject(size_t key, std::function<ObjectPtr()> creator);
 	private: // Attributes
 		LOG4CXX_DECLARE_PRIVATE_MEMBER_PTR(APRInitializerPrivate, m_priv)
 	private: // Class methods