*** lib/Readonly-orig.pm        2016-01-27 11:21:02.875021600 -0500
--- lib/Readonly.pm     2016-01-27 19:12:43.312714100 -0500
***************
*** 298,303 ****
--- 298,305 ----
          my $badtype = _is_badtype (ref tied ${$_[0]});
          croak "$REASSIGN $badtype" if $badtype;
          croak "Readonly scalar must have only one value" if @_ > 2;
+         croak 'You meant $sca => $val not $sca = $val'
+             if @_ == 1 && defined ${$_[0]};

          my $tieobj = eval {tie ${$_[0]}, 'Readonly::Scalar', $_[1]};
          # Tie may have failed because user tried to tie a constant, or we screwed up somehow.