diff --git a/test/format-test.cc b/test/format-test.cc
index e81640e5..39da0d7b 100644
--- a/test/format-test.cc
+++ b/test/format-test.cc
@@ -771,7 +771,10 @@ TEST(FormatterTest, SpaceSign) {
 
 TEST(FormatterTest, SignNotTruncated) {
   wchar_t format_str[] = {L'{', L':',
-                          '+' | static_case<wchar_t>(1 << fmt::detail::num_bits<char>()), L'}', 0};
+                          '+' | static_cast<wchar_t>(
+                            1 << fmt::detail::num_bits<char>() 
+                            & static_cast<typename std::make_unsigned_t<wchar_t> >(-1) ),
+                          L'}', 0};
   EXPECT_THROW(format(format_str, 42), format_error);
 }