On Linux, this code produces: Segmentation fault I do not understand what is happening behind the scenes using ReadKey. But what I can tell is: my $inp = ReadKey 0; works just fine on Linux, and for me, also on Win 7 x64, perl 5.14.4 MSWin32-x86-multi-thread For the records: (v5.16.0) built for x86_64-linux-thread-multi, openSUSE 12.2 (x86_64) Hope to be of help to someone. Bogi