diff --git a/trunk/ripnews/net/nntp.rb b/trunk/ripnews/net/nntp.rb
index e80d20a..7590d76 100644
--- a/trunk/ripnews/net/nntp.rb
+++ b/trunk/ripnews/net/nntp.rb
@@ -104,7 +104,7 @@ class NNTP
     puts "*getresp* #{resp}" if @debuglevel > 0
     c = resp[0]
     case c
-      when c == nil then raise NNTPProtocolError, resp, caller
+      when c.nil? then raise NNTPProtocolError, resp, caller
       when c == '4' then raise NNTPTemporaryError, resp, caller
       when c == '5' then raise NNTPPermanentError, resp, caller
       when '123'.include?(c) then raise NNTPProtocolError, resp, caller