diff --git a/lib/execjs/encoding.rb b/lib/execjs/encoding.rb
deleted file mode 100644
index 8296144..0000000
--- a/lib/execjs/encoding.rb
+++ /dev/null
@@ -1,26 +0,0 @@
-module ExecJS
-  # Encodes strings as UTF-8
-  module Encoding
-    if RUBY_ENGINE == 'jruby' || RUBY_ENGINE == 'rbx'
-      # workaround for jruby bug http://jira.codehaus.org/browse/JRUBY-6588
-      # workaround for rbx bug https://github.com/rubinius/rubinius/issues/1729
-      def encode(string)
-        if string.encoding == ::Encoding::BINARY
-          data = string.dup
-          data.force_encoding(::Encoding::UTF_8)
-
-          unless data.valid_encoding?
-            raise ::Encoding::UndefinedConversionError, "Could not encode binary data #{string.dump} as UTF-8"
-          end
-        else
-          data = string.encode(::Encoding::UTF_8)
-        end
-        data
-      end
-    else
-      def encode(string)
-        string.encode(::Encoding::UTF_8)
-      end
-    end
-  end
-end
diff --git a/lib/execjs/runtime.rb b/lib/execjs/runtime.rb
index 822bf5a..726e57b 100644
--- a/lib/execjs/runtime.rb
+++ b/lib/execjs/runtime.rb
@@ -1,11 +1,7 @@
-require "execjs/encoding"
-
 module ExecJS
   # Abstract base class for runtimes
   class Runtime
     class Context
-      include Encoding
-
       def initialize(runtime, source = "", options = {})
       end