diff --git a/winixd/core/filelog.cpp b/winixd/core/filelog.cpp
index f5844b5..717ae06 100644
--- a/winixd/core/filelog.cpp
+++ b/winixd/core/filelog.cpp
@@ -5,7 +5,7 @@
  */
 
 /*
- * Copyright (c) 2018, Tomasz Sowa
+ * Copyright (c) 2018-2019, Tomasz Sowa
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -95,6 +95,7 @@ PT::Date FileLog::get_local_date(const PT::Date & date)
 {
 	if( time_zones )
 	{
+		Lock lock(synchro);
 		TimeZone * tz = time_zones->GetZone(log_time_zone_id);
 
 		if( tz )
diff --git a/winixd/core/log.cpp b/winixd/core/log.cpp
index 0abd1d5..0b22d0c 100644
--- a/winixd/core/log.cpp
+++ b/winixd/core/log.cpp
@@ -5,7 +5,7 @@
  */
 
 /* 
- * Copyright (c) 2008-2018, Tomasz Sowa
+ * Copyright (c) 2008-2019, Tomasz Sowa
  * All rights reserved.
  * 
  * Redistribution and use in source and binary forms, with or without
@@ -77,7 +77,7 @@ void Log::PrintDate(const PT::Date & date)
 	FileLog * winix_file_log = dynamic_cast<FileLog*>(file_log);
 
 	if( winix_file_log )
-		(*this) << winix_file_log->get_local_date(date);
+		(*this) << winix_file_log->get_local_date(date); // synchronization is made in get_local_date
 	else
 		(*this) << date;
 }
@@ -250,17 +250,18 @@ return *this;
 }
 
 
-Log & Log::SystemErr(int err)
-{
-	(*this) << "errno: " << err;
-
-	const char * err_msg = strerror(err);
-
-	if( err_msg )
-		(*this) << " (" << err_msg << ")";
-
-	return *this;
-}
+//Log & Log::SystemErr(int err)
+//{
+//	(*this) << "errno: " << err;
+//
+//  // strerror is not thread safe and we now use Log in each thread
+//	const char * err_msg = strerror(err);
+//
+//	if( err_msg )
+//		(*this) << " (" << err_msg << ")";
+//
+//	return *this;
+//}
 
 
 
diff --git a/winixd/core/log.h b/winixd/core/log.h
index ed4c20f..f016db6 100644
--- a/winixd/core/log.h
+++ b/winixd/core/log.h
@@ -5,7 +5,7 @@
  */
 
 /* 
- * Copyright (c) 2008-2018, Tomasz Sowa
+ * Copyright (c) 2008-2019, Tomasz Sowa
  * All rights reserved.
  * 
  * Redistribution and use in source and binary forms, with or without
@@ -91,7 +91,7 @@ public:
 	virtual Log & LogBinary(const char * blob, size_t blob_len);
 	virtual Log & LogBinary(const std::string & blob);
 
-	virtual Log & SystemErr(int err);
+	//virtual Log & SystemErr(int err);
 
 
 private: