diff --git a/lib/aliyun/oss/http.rb b/lib/aliyun/oss/http.rb
index 9dde80a..1a60172 100644
--- a/lib/aliyun/oss/http.rb
+++ b/lib/aliyun/oss/http.rb
@@ -4,6 +4,18 @@
 require 'resolv'
 require 'fiber'
 
+module RestClientRefinements
+  # Refine rest-client to exclude the 'Content-Length' header when
+  # 'Transfer-Encoding' is set to 'chuncked' exclusively in Aliyun::OSS:HTTP. This may be a problem for
+  # some http servers like tengine.
+  refine RestClient::Payload::Base do
+    def headers
+      ({'content-length' => size.to_s} if size) || {}
+    end
+  end
+end
+
+
 module Aliyun
   module OSS
 
@@ -31,6 +43,7 @@ module OSS
     #     stream << "hello world"
     #   end
     class HTTP
+      using RestClientRefinements
 
       DEFAULT_CONTENT_TYPE = 'application/octet-stream'
       DEFAULT_ACCEPT_ENCODING = 'identity'
@@ -307,16 +320,3 @@ def get_user_agent
     end # HTTP
   end # OSS
 end # Aliyun
-
-# Monkey patch rest-client to exclude the 'Content-Length' header when
-# 'Transfer-Encoding' is set to 'chuncked'. This may be a problem for
-# some http servers like tengine.
-module RestClient
-  module Payload
-    class Base
-      def headers
-        ({'content-length' => size.to_s} if size) || {}
-      end
-    end
-  end
-end
diff --git a/lib/aliyun/oss/protocol.rb b/lib/aliyun/oss/protocol.rb
index 41d1398..01874d3 100644
--- a/lib/aliyun/oss/protocol.rb
+++ b/lib/aliyun/oss/protocol.rb
@@ -79,7 +79,7 @@ def list_buckets(opts = {})
         update_if_exists(
           more, {
             :limit => ->(x) { x.to_i },
-            :truncated => ->(x) { x.to_bool }
+            :truncated => ->(x) { Util.to_bool(x) }
           }
         )
 
@@ -413,7 +413,7 @@ def get_bucket_referer(name)
         doc = parse_xml(r.body)
         opts = {
           :allow_empty =>
-            get_node_text(doc.root, 'AllowEmptyReferer', &:to_bool),
+            get_node_text(doc.root, 'AllowEmptyReferer') { |x| Util.to_bool(x) },
           :whitelist => doc.css("RefererList Referer").map(&:text)
         }
 
@@ -790,7 +790,7 @@ def list_objects(bucket_name, opts = {})
         update_if_exists(
           more, {
             :limit => ->(x) { x.to_i },
-            :truncated => ->(x) { x.to_bool },
+            :truncated => ->(x) { Util.to_bool(x) },
             :delimiter => ->(x) { decode_key(x, encoding) },
             :marker => ->(x) { decode_key(x, encoding) },
             :next_marker => ->(x) { decode_key(x, encoding) }
@@ -1412,7 +1412,7 @@ def list_multipart_uploads(bucket_name, opts = {})
         update_if_exists(
           more, {
             :limit => ->(x) { x.to_i },
-            :truncated => ->(x) { x.to_bool },
+            :truncated => ->(x) { Util.to_bool(x) },
             :key_marker => ->(x) { decode_key(x, encoding) },
             :next_key_marker => ->(x) { decode_key(x, encoding) }
           }
@@ -1476,7 +1476,7 @@ def list_parts(bucket_name, object_name, txn_id, opts = {})
         update_if_exists(
           more, {
             :limit => ->(x) { x.to_i },
-            :truncated => ->(x) { x.to_bool }
+            :truncated => ->(x) { Util.to_bool(x) }
           }
         )
 
diff --git a/lib/aliyun/oss/util.rb b/lib/aliyun/oss/util.rb
index 7dc595d..a1971a5 100644
--- a/lib/aliyun/oss/util.rb
+++ b/lib/aliyun/oss/util.rb
@@ -97,17 +97,14 @@ def ensure_bucket_name_valid(name)
           unless (name =~ %r|^[a-z0-9][a-z0-9-]{1,61}[a-z0-9]$|)
             fail ClientError, "The bucket name is invalid."
           end
-        end  
+        end
+
+        def to_bool(string)
+          return true if string =~ /^true$/i
+          false
+        end
 
       end # self
     end # Util
   end # OSS
-end # Aliyun
-
-# Monkey patch to support #to_bool
-class String
-  def to_bool
-    return true if self =~ /^true$/i
-    false
-  end
-end
\ No newline at end of file
+end # Aliyun
\ No newline at end of file