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 <p><em>Installing on Debian/Ubuntu:</em></p>
 
-<p><code>sudo apt-get install libcurl4-gnutls-dev libopenssl-ruby libxml2 libxml2-dev libxslt1-dev</code></p>
+<p><code>sudo apt-get install libcurl4-gnutls-dev libopenssl-ruby libxml2 libxml2-dev libxslt1-dev ruby-dev</code></p>
 
 <p><code>git clone https://github.com/wpscanteam/wpscan.git</code></p>