Two self-described “grammar vigilantes” were sentenced to one year of probation and have been banned from all National Parks after they were caught “correcting” a a historical sign at the Desert View Watchtower on the South Rim of Grand Canyon National Park.

Jeff Michael Deck, 28, of Massachusetts and Benjamin Douglas Herson, 28, of Virginia, pled guilty to conspiracy to vandalize government property.

The men were on a tour of the United States from March to May 2008 with a purpose to stamp out typos in public signage and other venues, according to a news release from the U.S. Attorney’s Office in Arizona.

A rare hand painted sign hangs in the Watchtower and is considered irreplaceable, the release said.

The pair came across the sign and found “a few errors,” they wrote on a Web site, which is how authorities learned about the vandalism.

They waited for a ranger to leave the area and then used a permanent marker and white out to correct the sign.

“Those marks really didn’t blend in well at all,” the Web site said. “I was reluctant to disfigure the sign any further …”

In addition to not being able to visit national parks during their probation periods, the men are prohibited from making any modifications to any public signs and must place a statement on their Web site educating others about the historical and archeological impact of vandalizing signs in national parks.

They will also pay restitution in the amount of $3,035, which will be used to attempt to repair the sign.

On Friday, the Web site http://www.jeffdeck.com/teal/ posted the following message: “Statement on the signage of our National Parks and public lands to come”

Here is a photo of Deck at the Grand Canyon from the Web site, courtesy of the U.S. Attorney’s Office: