The public administration ministry issued an order re-fixing the date on Tuesday.
It earlier set June 12 as the Shab-e-Qadr holiday, considering May 17 as the beginning of Ramadan.
But the month in Arabic calendar started a day later as the moon was not sighted.
With the changed schedule, Muslims will pray overnight on June 12 and have the next day as a holiday.
No change has been brought to the Eid-ul-Fitr holidays of June 15 to June 17 yet. But the Eid holidays will be extended by a day if Ramadan lasts 30 days.