diff --git a/util/makedefs.c b/util/makedefs.c
index 1470dfb92..34978d47c 100644
--- a/util/makedefs.c
+++ b/util/makedefs.c
@@ -751,7 +751,7 @@ static const char *window_opts[] = {
 		"Gem",
 #endif
 #ifdef MSWIN_GRAPHICS
-		"Win32",
+		"mswin",
 #endif
 #ifdef BEOS_GRAPHICS
 		"BeOS InterfaceKit",