Ameren customers, prepare yourselves for yet another increase in your electric bill.

The utility will be able to charge an additional $121.5 million to its customers starting May 12 of 2015.

The Public Service Commission released an updated estimate of the amount Ameren can charge customers following a rate increase.

Commission staff say the average residential customer will see an increase of $5.45 a month on their electric bill.

The $121.5 million increase is less than half the $264 million Ameren initially requested in July of 2014.

But it’s higher than the $108 million estimate provided by staff Wednesday when the commissioners approved the increase.

The updated estimate incorporates other elements of that decision.