Edit: The original title was "Rendering m([spellcheck=false]) results in <div spellcheck="true">", but there are more issues, see below.

As mentioned in MithrilJS/docs#20 by @anonghuser, m([spellcheck=false]) results in <div spellcheck="true">, it should obviously be false.

I don't know if this should be fixed though. In scenarios where you want it not set, statically, you can omit the attribute. For dynamic scenarios the attrs object is a better method.