Replace sans-serif and Arial fonts with Ubuntu

fonts.conf

<!--?xml version="1.0"?>-->
<!--DOCTYPE fontconfig SYSTEM "fonts.dtd">-->
<!-- ~/.fonts.conf for per-user font configuration -->
<fontconfig>
    <alias>
        <family>sans-serif</family>
        <prefer>
            <family>Ubuntu</family>
        </prefer>
    </alias>
    <alias>
        <family>monospace</family>
        <prefer>
            <family>Ubuntu Mono</family>
        </prefer>
    </alias>
    <match>
        <test name="family"><string>Arial</string></test>
        <edit name="family" mode="prepend" binding="strong">
            <string>Ubuntu</string>
            <string>Arial</string>
        </edit>
    </match>
    <match>
        <test name="family"><string>helvetica</string></test>
        <edit name="family" mode="prepend" binding="strong">
            <string>Ubuntu</string>
            <string>Helvetica</string>
        </edit>
    </match>

</fontconfig>

The default sans-serif font and Arial commonly used by web sites render capital I (eye) and lowercase l (ell) indistinguishably. I got burned by a shortened link from goo.gl and started looking into what I could do to fix it. I put the above in ~/.fonts.conf and it replaces sans-serif and Arial with Ubuntu.

When I wrote the above comment, I noticed that Helvetica had same problem so I'm replacing it also. I wonder if one Match clause could do it?