diff --git a/dlls/ntdll/tests/string.c b/dlls/ntdll/tests/string.c
index 6f4d85bdd85..16c11926016 100644
--- a/dlls/ntdll/tests/string.c
+++ b/dlls/ntdll/tests/string.c
@@ -621,11 +621,13 @@ static void one_ui64toa_test(int test_num, const ulonglong2str_t *ulonglong2str)
     dest_str[LARGE_STRI_BUFFER_LENGTH] = '\0';
     result = p_ui64toa(ulonglong2str->value, dest_str, ulonglong2str->base);
     ok(result == dest_str,
-       "(test %d): _ui64toa(%Lu, [out], %d) has result %p, expected: %p\n",
-       test_num, ulonglong2str->value, ulonglong2str->base, result, dest_str);
+       "(test %d): _ui64toa(%08x%08x, [out], %d) has result %p, expected: %p\n",
+       test_num, (DWORD)(ulonglong2str->value >> 32), (DWORD)ulonglong2str->value,
+       ulonglong2str->base, result, dest_str);
     ok(memcmp(dest_str, ulonglong2str->Buffer, LARGE_STRI_BUFFER_LENGTH) == 0,
-       "(test %d): _ui64toa(%Lu, [out], %d) assigns string \"%s\", expected: \"%s\"\n",
-       test_num, ulonglong2str->value, ulonglong2str->base, dest_str, ulonglong2str->Buffer);
+       "(test %d): _ui64toa(%08x%08x, [out], %d) assigns string \"%s\", expected: \"%s\"\n",
+       test_num, (DWORD)(ulonglong2str->value >> 32), (DWORD)ulonglong2str->value,
+       ulonglong2str->base, dest_str, ulonglong2str->Buffer);
 }