diff --git a/lib/net/ftp.rb b/lib/net/ftp.rb
index b3ebaf68af..2e55222fbf 100644
--- a/lib/net/ftp.rb
+++ b/lib/net/ftp.rb
@@ -1362,7 +1362,7 @@ module Net
         raise FTPReplyError, resp
       end
       if m = /\((?<d>[!-~])\k<d>\k<d>(?<port>\d+)\k<d>\)/.match(resp)
-        return @sock.remote_address.ip_address, m["port"].to_i
+        return @bare_sock.remote_address.ip_address, m["port"].to_i
       else
         raise FTPProtoError, resp
       end
diff --git a/test/net/ftp/test_ftp.rb b/test/net/ftp/test_ftp.rb
index 6acaf87216..708def13bb 100644
--- a/test/net/ftp/test_ftp.rb
+++ b/test/net/ftp/test_ftp.rb
@@ -114,7 +114,7 @@ class FTPTest < Test::Unit::TestCase
     sock = OpenStruct.new
     sock.remote_address = OpenStruct.new
     sock.remote_address.ip_address = "1080:0000:0000:0000:0008:0800:200c:417a"
-    ftp.instance_variable_set(:@sock, sock)
+    ftp.instance_variable_set(:@bare_sock, sock)
     host, port = ftp.send(:parse229, "229 Entering Passive Mode (|||3106|)")
     assert_equal("1080:0000:0000:0000:0008:0800:200c:417a", host)
     assert_equal(3106, port)