Well, by the time I'd seen your guys' responses, I'd already had Qt recompiling without that "-Zc:wchar_t-" flag. While simply adding #include <wchar.h> would probably have been far easier (not to mention Qt-compliant), everything seems to be working perfectly well. Qt isn't spitting out any warnings or errors, qmake is building everything just fine, SIGNALS and SLOTS are working as per usual, and SFML and is most pleased.

So, for the record, while simply doing the #include should work (I didn't try it myself, but it makes all the sense in the world), recompiling Qt without the flag seems to work as well.

Though I am just a newbie and for all I know qmake is crying in desperation.