should_validate_numericality_of less_than/greater_than works incorrectly with floating point numbers

[mcm8]

my_model_spec.rb:
should_validate_numericality_of :testfield, :less_than => 10.1

my_model.rb
validates_length_of :testfield, :less_than => 10.1

Gives the following error:
'MyModel should ensure numericality of testfield is less than 10.1' FAILED
Expected MyModel to be invalid when testfield is greater than 9.1

The equivalent error happens on :greater_than (but NOT on the _or_equal versions).
(A workaround for floating point numbers ending in .0 is to only specify the integer part on the validator in the model class - in this case no error appears.)