Test RUBY_VERSION rather than VERSION (which no longer exists in 1.9).

lib/process_shared.rb

@@ -1,6 +1,6 @@
 require 'ffi'
 
-if VERSION =~ /^1.8/
+if RUBY_VERSION =~ /^1.8/
   require 'process_shared/define_singleton_method'
   
   module ProcessShared

spec/spec_helper.rb

@@ -1,4 +1,4 @@
-require 'rubygems' if VERSION =~ /^1.8/
+require 'rubygems' if RUBY_VERSION =~ /^1.8/
 gem 'minitest'
 require 'minitest/spec'
 require 'minitest/autorun'