diff --git a/xpcom/tests/gtest/TestStrings.cpp b/xpcom/tests/gtest/TestStrings.cpp
    --- a/xpcom/tests/gtest/TestStrings.cpp
    +++ b/xpcom/tests/gtest/TestStrings.cpp
    @@ -2457,7 +2457,7 @@ static_assert(testStringA.IsTerminated()
     static_assert(testStringA.GetDataFlags() ==
                   (nsLiteralString::DataFlags::LITERAL |
                    nsLiteralString::DataFlags::TERMINATED));
    -static_assert(*testStringA.Data() == 'a');
    +static_assert(*static_cast<const char16_t*>(testStringA.Data()) == 'a');
     static_assert(1 == testStringA.Length());
     static_assert(testStringA.CharAt(0) == 'a');
     static_assert(testStringA[0] == 'a');