Spree_watermark fails during initialization

[skatkov]

I've added "spree_watermark" gem to spree project
spree -v = 1.3.3
rails -v = 3.2.13
ruby -v = ruby 1.9.3p194 (2012-04-20 revision 35410) [x86_64-darwin11.4.0]

Project fails to initialize (rails s) with following error:
/Users/lun/.rvm/gems/ruby-1.9.3-p194/gems/spree_watermark-0.50.4/lib/spree_watermark_hooks.rb:1:in <top (required)>': uninitialized constant Spree::ThemeSupport (NameError) from /Users/lun/.rvm/gems/ruby-1.9.3-p194/gems/polyglot-0.3.3/lib/polyglot.rb:63:inrequire'
from /Users/lun/.rvm/gems/ruby-1.9.3-p194/gems/polyglot-0.3.3/lib/polyglot.rb:63:in require' from /Users/lun/.rvm/gems/ruby-1.9.3-p194/gems/spree_watermark-0.50.4/lib/spree_watermark.rb:2:in<top (required)>'
from /Users/lun/.rvm/gems/ruby-1.9.3-p194/gems/bundler-1.3.5/lib/bundler/runtime.rb:72:in require' from /Users/lun/.rvm/gems/ruby-1.9.3-p194/gems/bundler-1.3.5/lib/bundler/runtime.rb:72:inblock (2 levels) in require'
from /Users/lun/.rvm/gems/ruby-1.9.3-p194/gems/bundler-1.3.5/lib/bundler/runtime.rb:70:in each' from /Users/lun/.rvm/gems/ruby-1.9.3-p194/gems/bundler-1.3.5/lib/bundler/runtime.rb:70:inblock in require'
from /Users/lun/.rvm/gems/ruby-1.9.3-p194/gems/bundler-1.3.5/lib/bundler/runtime.rb:59:in each' from /Users/lun/.rvm/gems/ruby-1.9.3-p194/gems/bundler-1.3.5/lib/bundler/runtime.rb:59:inrequire'
from /Users/lun/.rvm/gems/ruby-1.9.3-p194/gems/bundler-1.3.5/lib/bundler.rb:132:in require' from /Users/lun/code/gamestockgfx/config/application.rb:7:in<top (required)>'
from /Users/lun/.rvm/gems/ruby-1.9.3-p194/gems/railties-3.2.13/lib/rails/commands.rb:53:in require' from /Users/lun/.rvm/gems/ruby-1.9.3-p194/gems/railties-3.2.13/lib/rails/commands.rb:53:inblock in <top (required)>'
from /Users/lun/.rvm/gems/ruby-1.9.3-p194/gems/railties-3.2.13/lib/rails/commands.rb:50:in tap' from /Users/lun/.rvm/gems/ruby-1.9.3-p194/gems/railties-3.2.13/lib/rails/commands.rb:50:in<top (required)>'
from script/rails:6:in require' from script/rails:6:in

'