diff --git a/lib/test_scanf.c b/lib/test_scanf.c
index b620cf7de503..a2707af2951a 100644
--- a/lib/test_scanf.c
+++ b/lib/test_scanf.c
@@ -606,7 +606,7 @@ static void __init numbers_slice(void)
 #define test_number_prefix(T, str, scan_fmt, expect0, expect1, n_args, fn)	\
 do {										\
 	const T expect[2] = { expect0, expect1 };				\
-	T result[2] = {~expect[0], ~expect[1]};					\
+	T result[2] = { (T)~expect[0], (T)~expect[1] };				\
 										\
 	_test(fn, &expect, str, scan_fmt, n_args, &result[0], &result[1]);	\
 } while (0)