Rails reCaptcha gem - Not accepting theme option identified in Google's docs

Rails
1

I’m using the recaptcha gem (GitHub - ambethia/recaptcha: ReCaptcha helpers for ruby apps) but have
been
unable to change from the default theme. The google documentation
indicates
that there are four base themes, one of which is ‘white’. The
recaptcha_tags docs
identify a :display option:

:display - Takes a hash containing the theme and tabindex options

per the API. (default nil)

I’m calling the function this way:

<%= recaptcha_tags :display => { :theme => "white" } %>

But I only get the default theme, not the white theme. I inserted a
puts()
into the source of the recaptcha gem where the options are parsed and
get
the following:

Options: {:public_key=>"XXXXXXXXXXXXX-YYYYYYYYYYYYYYY",

:error=>“expression”}

I’ve tried every variation I can think of to pass a :display option with
a
hash of :theme => “white” and can’t get it to work. What am I doing
wrong
here?