diff --git a/config/auto/attributes/test_c.in b/config/auto/attributes/test_c.in
index eb5262c..896da8b 100644
--- a/config/auto/attributes/test_c.in
+++ b/config/auto/attributes/test_c.in
@@ -42,7 +42,7 @@ coldfunc(int x);
 
 
 static int
-useless(void) { int x __attribute__unused__; return 0; }
+useless(int x __attribute__unused__) { int y __attribute__unused__; return 0; }
 
 
 /* as long as the file compiles, everything is okay */