[code]Installing nokogiri (1.4.3.1) with native extensions /Users/username/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/rubygems/installer.rb:483:in `rescue in block in build_extensions’: ERROR: Failed to build gem native extension. (Gem::Installer::ExtensionBuildError)[/code] Installing the nokogiri gem was throwing the above exception, but the clue to the problem lay at the end of the stack trace where the process was complaining about: [code]ld: in /opt/local/lib/libz.1.dylib, file was built for i386 which is not the architecture being linked (x86_64)[/code] the fix courtesy of : http://www.refresherate.com/2010/01/08/fixing-ld-warning-in-usrlocalliblibz-dylib-file-is-not-of-required-architecture/ [code]sudo mv /opt/local/lib/libz.dylib /opt/local/lib/libz.dylib.original sudo /Developer/SDKs/MacOSX10.6.sdk/usr/lib/libz.dylib /opt/local/lib/ sudo mv /opt/local/lib/libz.1.dylib /opt/local/lib/libz.1.dylib.original sudo cp /Developer/SDKs/MacOSX10.6.sdk/usr/lib/libz.1.dylib /opt/local/lib/[/code]