SAN FRANCISCO (CBS SF) — Two cracked windows have been discovered at San Francisco’s tallest building, the Salesforce Tower, months after cracked windows were found a block away at the sinking Millennium Tower.

Building inspectors confirmed one south-facing window on the 12th floor and an east-facing window on the 14th floor are cracked on the inside.

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It’s not clear what caused them to crack.

A spokesperson for the building’s owner says since the damage is on the inside there is no danger of glass falling onto the street.

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The panes are set to be replaced in the coming weeks.

In September, a cracked window caused new concern at the problem-plagued Millennium Tower which has been sinking and tilting slightly. It was later determined an unknown exterior impact caused the cracked window.

In October, more cracked glass was found on the building’s exterior. Officials say the sinking is not to blame for the cracked windows.

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Also last September, cracks in steel beams at the new Salesforce Transit Center, adjacent to the Salesforce Tower, forced the closure of the transit center, with transbay service once again provided from a nearby temporary transbay terminal.