Errno::EACCES: Permission denied

[morgoth]

hey, when loading gem, I got

irb(main):001:0> require 'rbcalc'
Errno::EACCES: Permission denied @ rb_file_s_symlink - (/home/wojtek/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/rbcalc-0.1.0/vendor/bcalc/libbcalcdds.so, /usr/local/lib/libbcalcdds.so)
	from /home/wojtek/.rbenv/versions/2.3.1/lib/ruby/2.3.0/fileutils.rb:358:in `symlink'
	from /home/wojtek/.rbenv/versions/2.3.1/lib/ruby/2.3.0/fileutils.rb:358:in `block in ln_s'
	from /home/wojtek/.rbenv/versions/2.3.1/lib/ruby/2.3.0/fileutils.rb:1587:in `fu_each_src_dest0'
	from /home/wojtek/.rbenv/versions/2.3.1/lib/ruby/2.3.0/fileutils.rb:356:in `ln_s'
	from /home/wojtek/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/rbcalc-0.1.0/lib/rbcalc.rb:43:in `init!'
	from /home/wojtek/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/rbcalc-0.1.0/lib/rbcalc.rb:54:in `<top (required)>'
	from /home/wojtek/.rbenv/versions/2.3.1/lib/ruby/site_ruby/2.3.0/rubygems/core_ext/kernel_require.rb:133:in `require'
	from /home/wojtek/.rbenv/versions/2.3.1/lib/ruby/site_ruby/2.3.0/rubygems/core_ext/kernel_require.rb:133:in `rescue in require'
	from /home/wojtek/.rbenv/versions/2.3.1/lib/ruby/site_ruby/2.3.0/rubygems/core_ext/kernel_require.rb:40:in `require'
	from (irb):1
	from /home/wojtek/.rbenv/versions/2.3.1/bin/irb:11:in `<main>'