diff --git a/src/knx/logger.h b/src/knx/logger.h
index 2c2c26c..ffcaa16 100644
--- a/src/knx/logger.h
+++ b/src/knx/logger.h
@@ -16,6 +16,7 @@ Usage:
 
 #include <utility>
 #include <string>
+#include <cstdarg>
 
 #include "platform.h"