(CNN) Microsoft has made its typographical decree: Two spaces between sentences is too many.
The style choice will now be marked as an error in Microsoft Word -- and users who press the space bar twice after a period will be met with those dreaded blue squiggly lines.
The change, first noticed by University of Denver law professor Alan Chen and reported by tech outlet The Verge, is rolling out gradually across Word, so users may not notice it until their software updates.
The habit of using two spaces is a relic from the era of typewriters, when typists spaced twice to more clearly define the end of a sentence. Characters were "monospaced" back then, which means they took up the same amount of space on the page -- today, most fonts adjust the width of characters so sentences are easier to read.
Very few style guides advise using two spaces after a period. The APA, Chicago Manual of Style, AP and US Government Printing Office Style Manual all recommend a single space between sentences. The contemporary benefits of using it are few, aside from taking up more space on a page.
If you absolutely cannot part with your beloved double space, here's what you can do: When Word marks it as an error, right click to view your options. You can ask Word to ignore this issue when it comes up again or view every grammatical issue the software will mark and remove spacing from the list of errors.