diff --git a/es-core/src/Log.cpp b/es-core/src/Log.cpp
index 821852a12..e66fb31ea 100644
--- a/es-core/src/Log.cpp
+++ b/es-core/src/Log.cpp
@@ -4,6 +4,7 @@
 //  Log.cpp
 //
 //  Log output.
+//  This class is thread safe.
 //
 
 #include "Log.h"
diff --git a/es-core/src/Log.h b/es-core/src/Log.h
index 0f412b4eb..0f165cd04 100644
--- a/es-core/src/Log.h
+++ b/es-core/src/Log.h
@@ -4,6 +4,7 @@
 //  Log.h
 //
 //  Log output.
+//  This class is thread safe.
 //
 
 #ifndef ES_CORE_LOG_H