title: "Gtk-WARNING **: Locale not supported by C library. Using the fallback 'C' locale." on OS X
body: <h3>Background information:</h3>
  
  <p>I use Mac OSX Yosemite.</p>
  
  <p>I've installed <code>gtk+</code> using <code>brew install gtk+</code> and fixed the errors using <code>export PKG_CONFIG_PATH=/opt/X11/lib/pkgconfig</code>.</p>
  
  <p>I've build my program using <code>make</code> but when I try to run it I get a warning like this:</p>
  
  <pre><code>(process:16182): Gtk-WARNING **: Locale not supported by C library.
          Using the fallback 'C' locale.
  </code></pre>
  
  <h2>Problem: I cannot find any solutions for OS X for this particular problem.</h2>
  
  <h3>What I've learnt so far:</h3>
  
  <ol>
  <li><p>In this thread (<a href="https://stackoverflow.com/questions/20366533/gtk-warning-locale-not-supported-by-c-library-while-using-several-python-mo">Gtk-WARNING **: Locale not supported by C library. while using several Python modules (mayavi, spectral)</a>) they suggests using: <blockquote> <code>ipython --pylab=wx</code> instead of <code>ipython --pylab=osx</code></blockquote>
  but I've got no idea how python can be related to my problem (my program is written in C - the same applies to <code>gtk+</code> I guess)</p></li>
  <li><p>You can find a lot of threads on this issue like this one: (<a href="https://askubuntu.com/questions/359753/gtk-warning-locale-not-supported-by-c-library-when-starting-apps-from-th">Gtk-WARNING **: Locale not supported by C library. when starting apps from the commandline</a>) but they mainly refer to Linux and/or Ubuntu. <br>Most of the answers use a command like this sooner or later:</p>
  
  <pre><code> sudo dpkg-reconfigure locales
  </code></pre>
  
  <p>But there is no <code>dpkg</code> on OS X.</p></li>
  </ol>