A French Jew strolled into his synagogue dressed as a gun-toting jihadist, shouting “Allahu Akbar” — in an attempt, he said, to “lighten the mood” after last week’s terrorist attacks.

The 40-year-old man was attending services for the festival of Purim, a costumed celebration, toting a fake submachine gun at the Chabad Lubavitch synagogue in an eastern Paris suburb last week.

The prank was a dud, and the unnamed man drew the attention of local cops, who ordered him to show up at a local police station on Friday.

“I think I made a big mistake,” he told Le Parisien newspaper.

The synagogue is located in Vincennes, where gunmen shot four Jews last year.