orthography - "Updatable" vs. "Updateable": which is correct?

Which spelling is correct, "updatable" or "updateable"?

For example, "The file is not updat(e)able."

By the way, I did go to Google and ref.dic.com for this first, and they both seem to indicate that both spellings are correct. If they are indeed both correct, which is more widely accepted?

Answer

Google Ngrams shows that updatable is currently much more prevalent: