diff --git a/lib/net/http/generic_request.rb b/lib/net/http/generic_request.rb
index 003f59d0ac..fe18d22921 100644
--- a/lib/net/http/generic_request.rb
+++ b/lib/net/http/generic_request.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 # HTTPGenericRequest is the parent of the Net::HTTPRequest class.
 # Do not use this directly; use a subclass of Net::HTTPRequest.
 #
@@ -241,7 +241,7 @@ def encode_multipart_form_data(out, params, opt)
     boundary ||= SecureRandom.urlsafe_base64(40)
     chunked_p = chunked?
 
-    buf = ''
+    buf = ''.dup
     params.each do |key, value, h={}|
       key = quote_string(key, charset)
       filename =
@@ -326,7 +326,7 @@ def write_header(sock, ver, path)
     if /[\r\n]/ =~ reqline
       raise ArgumentError, "A Request-Line must not contain CR or LF"
     end
-    buf = ""
+    buf = ''.dup
     buf << reqline << "\r\n"
     each_capitalized do |k,v|
       buf << "#{k}: #{v}\r\n"
diff --git a/lib/net/http/header.rb b/lib/net/http/header.rb
index 8641be4eae..623a144350 100644
--- a/lib/net/http/header.rb
+++ b/lib/net/http/header.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 # The HTTPHeader module defines methods for reading and writing
 # HTTP headers.
 #
diff --git a/lib/net/http/response.rb b/lib/net/http/response.rb
index 5a94f95694..4974dee771 100644
--- a/lib/net/http/response.rb
+++ b/lib/net/http/response.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 # HTTP response class.
 #
 # This class wraps together the response header and the response body (the
@@ -345,7 +345,7 @@ def procdest(dest, block)
     if block
       Net::ReadAdapter.new(block)
     else
-      dest || ''
+      dest || ''.dup
     end
   end