Failed on Windows 7 x64 Ruby enviorment

[rufushuang]

C:\Users\Administrator\Desktop>pcap_tools data2.pcap
Mode : http
C:/Ruby193/lib/ruby/gems/1.9.1/gems/popen4-0.1.2/lib/popen4.rb:49:in `popen4': uninitialized constant POpen4::Open4 (NameError)
        from C:/Ruby193/lib/ruby/gems/1.9.1/gems/pcap_tools-0.0.7/lib/pcap_tools/loader.rb:102:in `load_file'
        from C:/Ruby193/lib/ruby/gems/1.9.1/gems/pcap_tools-0.0.7/bin/pcap_tools:138:in `block in <top (required)>'
        from C:/Ruby193/lib/ruby/gems/1.9.1/gems/pcap_tools-0.0.7/bin/pcap_tools:137:in `each'
        from C:/Ruby193/lib/ruby/gems/1.9.1/gems/pcap_tools-0.0.7/bin/pcap_tools:137:in `<top (required)>'
        from C:/Ruby193/bin/pcap_tools:23:in `load'
        from C:/Ruby193/bin/pcap_tools:23:in `<main>'

Is it quite a dependence to use popen?
some like svn2git has removed popen usage.