Metro is refunding some customers after a technical glitch under and overcharged riders for years.

Officials said “distance calculation errors” led to Metro charging customers five cents above and below the appropriate price for the distance they traveled but did not specify which routes were affected, DCist reported.

The issue affected fewer than 5 percent of Metro trips.

This summer, Metro will provide automatic credit to customers with registered SmarTrip cards who were overcharged by more than $2 between 2015 and 2017, according to DCist.

“We’re still in the process of going through the analysis to determine which riders were affected,” Metro spokesman Richard Jordan told the news website.

Since July 2014, undercharges led to about a $372,0000 loss for the agency, which has faced a budget crunch in recent years. Metro does not have plans to collect additional money from customers who were undercharged, WTOP reported.

The issue cost Metro about $124,000 each year or 0.007 percent of its operating budget.

The announcement comes a day after Metro hiked fares and implemented a new schedule on Sunday.