I saw this question How do I repair the corrupted files found by sfc /scannow? "Windows Resource Protection found corrupt files but was unable to fix some of them.", but it was for Windows 7. Running the sfc /scannow command on my installation of Windows 8.1 gave me this error:

Windows Resource Protection found corrupt files but was unable to fix some of them. Details are included in the CBS.Log windir\Logs\CBS\CBS.log. For example C:\Windows\Logs\CBS\CBS.log. Note that logging is currently not supported in offline servicing scenarios.

I ran chkdsk and it found no problems.