https://rt.cpan.org/Public/Bug/Display.html?id=108434

diff -Nur Proc-PID-File-1.27.old/File.pm Proc-PID-File-1.27/File.pm

--- Proc-PID-File-1.27.old/File.pm	2009-10-13 06:40:21.000000000 +0500

+++ Proc-PID-File-1.27/File.pm	2016-04-28 16:53:48.800782841 +0400

@@ -283,7 +283,8 @@

 		|| die qq/Cannot open pid file "$self->{path}": $!\n/;

 	flock($fh, LOCK_EX | LOCK_NB)

         || die qq/pid "$self->{path}" already locked: $!\n/;

-	my ($pid) = <$fh> =~ /^(\d+)/;

+	my $maybe = <$fh>;

+	my ($pid) = $maybe =~ /^(\d+)/ if (defined $maybe);

 	close $fh if @_ == 1;

 	$self->debug("read(\"$self->{path}\") = " . ($pid || ""));