diff --git a/src/inet/tests/TestInetCommonOptions.cpp b/src/inet/tests/TestInetCommonOptions.cpp
index b424f4b16577eb..727b6a107b28f1 100644
--- a/src/inet/tests/TestInetCommonOptions.cpp
+++ b/src/inet/tests/TestInetCommonOptions.cpp
@@ -26,7 +26,9 @@
 #ifndef __STDC_LIMIT_MACROS
 #define __STDC_LIMIT_MACROS
 #endif
+#ifndef __STDC_FORMAT_MACROS
 #define __STDC_FORMAT_MACROS
+#endif
 
 #include "TestInetCommonOptions.h"