bson 4.0.0 gem error : <p>I got this error while installing bson gem: (ruby 2.2.2, ubuntu 14.04 clean)</p>

<pre><code>ubuntu:/var/apps/real-fetcher$ gem install bson -v '4.0.0'
Building native extensions.  This could take a while...
ERROR:  Error installing bson:
    ERROR: Failed to build gem native extension.

    /home/ubuntu/.rvm/rubies/ruby-2.2.2/bin/ruby -r ./siteconf20160110-7126-18thkio.rb extconf.rb
creating Makefile

make "DESTDIR=" clean

make "DESTDIR="
compiling native.c
In file included from native.c:21:0:
native-endian.h:113:17: warning: '__bson_uint32_swap_slow' defined but not used [-Wunused-function]
 static uint32_t __bson_uint32_swap_slow(uint32_t v)
             ^
native-endian.h:137:17: warning: '__bson_uint64_swap_slow' defined but not used [-Wunused-function]
 static uint64_t __bson_uint64_swap_slow(uint64_t v)
             ^
native-endian.h:164:15: warning: '__bson_double_swap_slow' defined but not used [-Wunused-function]
 static double __bson_double_swap_slow(double v)
           ^
linking shared-object native.so
/usr/bin/ld: cannot find -lgmp
collect2: error: ld returned 1 exit status
make: *** [native.so] Error 1

make failed, exit code 2

Gem files will remain installed in /home/ubuntu/.rvm/gems/ruby-2.2.2/gems/bson-4.0.0 for inspection.
Results logged to /home/ubuntu/.rvm/gems/ruby-2.2.2/extensions/x86_64-linux/2.2.0/bson-4.0.0/gem_make.out
</code></pre>

<p>Can't find anything related on my searches.</p>

<p>I haven't tried anything yet and I'm not sure what to try.</p>
