note philkime I had something like this too but it doesn't work on Windows. Here is a stripped down example using Inline::C. On non-Windows (cygwin included), it outputs correctly: |ERROR| On Windows, it gives: || ERROR which shows you that the STDERR isn't being captured. <code> use File::Temp qw(tempfile); use Inline C; open my $olderr, '>&STDERR'; # save STDERR my ($fh, $fn) = tempfile(); open STDERR, '>&', $fh; test_err(); open STDERR, '>&', $olderr; # reset STDERR close $fh; open my $e, '<', $fn; my $err = <$e>; print "|$err|\n"; __END__ __C__ void test_err() { (void)fprintf (stderr, "ERROR"); } </code> 929318 930768