diff --git a/include/athena/FileWriter.hpp b/include/athena/FileWriter.hpp
index 8027189..1683b40 100644
--- a/include/athena/FileWriter.hpp
+++ b/include/athena/FileWriter.hpp
@@ -2,7 +2,9 @@
 #define FILEWRITER_HPP
 
 #if _WIN32
+#ifndef WIN32_LEAN_AND_MEAN
 #define WIN32_LEAN_AND_MEAN
+#endif
 #include <windows.h>
 #else
 #include <stdio.h>