4 files changed, 5 insertions, 5 deletions
diff --git a/lib/net/smtp.rb b/lib/net/smtp.rb
index 1302f3aa1d..a485fff9b4 100644
--- a/lib/net/smtp.rb
+++ b/lib/net/smtp.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 # = net/smtp.rb
 #
 # Copyright (c) 1999-2007 Yukihiro Matsumoto.
@@ -945,7 +945,7 @@ module Net
     end
 
     def recv_response
-      buf = ''
+      buf = ''.dup
       while true
         line = @socket.readline
         buf << line << "\n"
diff --git a/test/net/smtp/test_response.rb b/test/net/smtp/test_response.rb
index 79ac1d2d32..3cf909a762 100644
--- a/test/net/smtp/test_response.rb
+++ b/test/net/smtp/test_response.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'net/smtp'
 require 'test/unit'
 
diff --git a/test/net/smtp/test_smtp.rb b/test/net/smtp/test_smtp.rb
index 89a08cb17b..3a9749504d 100644
--- a/test/net/smtp/test_smtp.rb
+++ b/test/net/smtp/test_smtp.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'net/smtp'
 require 'stringio'
 require 'test/unit'
diff --git a/test/net/smtp/test_ssl_socket.rb b/test/net/smtp/test_ssl_socket.rb
index 354f413040..342391f159 100644
--- a/test/net/smtp/test_ssl_socket.rb
+++ b/test/net/smtp/test_ssl_socket.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 require 'net/smtp'
 require 'test/unit'