diff --git a/include/SDL_config.h.cmake b/include/SDL_config.h.cmake
index 23eb1205eb..0352922428 100644
--- a/include/SDL_config.h.cmake
+++ b/include/SDL_config.h.cmake
@@ -204,7 +204,7 @@
 #cmakedefine HAVE_POLL 1
 #cmakedefine HAVE__EXIT 1
 
-#elif __WIN32__
+#elif defined(__WIN32__)
 #cmakedefine HAVE_STDARG_H 1
 #cmakedefine HAVE_STDDEF_H 1
 #cmakedefine HAVE_FLOAT_H 1