Bug #1571: Hash Methods Behaving Inconsistently with Frozen Hashes http://redmine.ruby-lang.org/issues/show/1571 Author: Run Paint Run Run Status: Open, Priority: Normal ruby -v: ruby 1.9.2dev (2009-06-01 trunk 23614) [i686-linux] As per matz's request in [ruby-core:23714], here are the Hash methods I've found which do not raise RuntimeErrors when the Hash is frozen and the method wouldn't have changed it: Hash#merge!, e.g. h.merge!({}) Hash#update, e.g. h.update({}) Hash#reject!, e.g. {}.reject! {true} ---------------------------------------- http://redmine.ruby-lang.org