diff --git a/lib/libv8.rb b/lib/libv8.rb
index bc4cf63..770b1f2 100644
--- a/lib/libv8.rb
+++ b/lib/libv8.rb
@@ -1,13 +1,18 @@
-require 'mkmf'
+require 'rbconfig'
+
 require 'libv8/arch'
 module Libv8
 
   module_function
 
+  def config
+    Config::MAKEFILE_CONFIG
+  end
+
   def libv8_object(name)
-    filename = "#{libv8_source_path}/out/#{Libv8::Arch.libv8_arch}.release/libv8_#{name}.#{$LIBEXT}"
+    filename = "#{libv8_source_path}/out/#{Libv8::Arch.libv8_arch}.release/libv8_#{name}.#{config['LIBEXT']}"
     unless File.exists? filename
-      filename = "#{libv8_source_path}/out/#{Libv8::Arch.libv8_arch}.release/obj.target/tools/gyp/libv8_#{name}.#{$LIBEXT}"
+      filename = "#{libv8_source_path}/out/#{Libv8::Arch.libv8_arch}.release/obj.target/tools/gyp/libv8_#{name}.#{config['LIBEXT']}"
     end
     return filename
   end