diff --git a/ChangeLog b/ChangeLog
index 8d9d0978a8..01509e3e1b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Tue Aug  5 16:33:20 2008  Shugo Maeda  <shugo@ruby-lang.org>
+
+	* lib/net/imap.rb (disconnect): do not refer SSL::SSLSocket for
+	  environments without OpenSSL.  backported from trunk.
+	  fixed [ruby-dev:35755].
+
 Tue Aug  5 14:19:22 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* file.c (rb_stat_mode): generalized st_mode mask.
diff --git a/lib/net/imap.rb b/lib/net/imap.rb
index f8c0d3be4c..6162ffa0d0 100644
--- a/lib/net/imap.rb
+++ b/lib/net/imap.rb
@@ -284,9 +284,11 @@ module Net
 
     # Disconnects from the server.
     def disconnect
-      if SSL::SSLSocket === @sock
+      begin
+        # try to call SSL::SSLSocket#io.
         @sock.io.shutdown
-      else
+      rescue NoMethodError
+        # @sock is not an SSL::SSLSocket.
         @sock.shutdown
       end
       @receiver_thread.join