As New Yorkers head to the polls Tuesday to vote in the presidential primary, Republican front-runner Donald Trump is coming under fire on social media for an untimely mistake at a New York rally.

Speaking to supporters in Buffalo on Monday, Trump launched into a tribute to police and firefighters who responded to the World Trade Center attacks on Sept. 11, 2001. The only problem is, he got the date wrong.

“I wrote this out, and it’s very close to my heart because I was down there and I watched our police and our firemen down on 7/11, down at the World Trade Center right after it came down…” Trump mistakenly said.

Apparently, writing it down didn’t help Trump remember the date of the terror attacks.

Twitter erupted with criticism at Trump’s flub, with many making reference to the popular convenience store chain 7-Eleven.

“7-Eleven is one of those tragedies all Americans have to shoulder,” said Twitter user @ThirtyYearOld.

“When you stop by your local @7eleven today, make sure you thank the on-duty employee and tell them that @realDonaldTrump sent you,” @bostonrandy wrote.

So far, Trump has not commented about the mishap on his Twitter account.