Update: This problem only occurs when you install the ruby-mode package from MELPA, which is actually an older version of ruby-mode than ships with Emacs 23. Thanks to dgutov for the hint! When I upgraded to Emacs 24.3 I noticed that I could not write curly braces anymore in ruby-mode. All I got was this error: call-interactively: Symbol's value as variable is void: last-command-char The easiest w