diff --git a/include/boost/system/detail/snprintf.hpp b/include/boost/system/detail/snprintf.hpp
index a8b9c97..f54a351 100644
--- a/include/boost/system/detail/snprintf.hpp
+++ b/include/boost/system/detail/snprintf.hpp
@@ -49,7 +49,7 @@ inline void snprintf( char * buffer, std::size_t len, char const * format, ... )
 
 #else
 
-#if __GNUC__ >= 3
+#if defined(__GNUC__) && __GNUC__ >= 3
 __attribute__((__format__ (__printf__, 3, 4)))
 #endif
 inline void snprintf( char * buffer, std::size_t len, char const * format, ... )