Fix undefined constant error

Evidently this case is never hit as middleware because options is always specified, but if it is not, that constant is undefined.
Merge pull request #37 from MichaelXavier/patch-1

Fix undefined constant error
Preparing for v0.6.6 release
Merge pull request #38 from dplummer/v0.6.6-prep

Preparing for v0.6.6 release