diff --git a/lib/openid/server.rb b/lib/openid/server.rb
index 8fa1513..3a86e7d 100644
--- a/lib/openid/server.rb
+++ b/lib/openid/server.rb
@@ -1240,7 +1240,7 @@ module OpenID
       # Raises ProtocolError when the query does not seem to be a valid
       # OpenID request.
       def decode(query)
-        if query.nil? or query.length == 0
+        if query.nil? or query.empty? == 0
           return nil
         end