# EPUBCheck MED-009: zero-length overlay clip, how to fix it

Source: https://epubcc.com/epubcheck/med-009/ (updated 2026-11-04)

EPUBCheck MED-009 is an error message: “The time specified in the clipBegin attribute must not be the same as clipEnd.” In a media overlay, a clip's clipBegin and clipEnd are the same, so the clip has no duration. Nothing would play for that phrase, and EPUBCheck reports it as an error.

- Official message (EPUBCheck 5.4.0): The time specified in the clipBegin attribute must not be the same as clipEnd.
- Default severity: Error

## Typical causes

- A clip that was cut to zero length when editing the narration.
- An alignment tool that could not place a phrase and wrote the same time twice.

## How to fix it

1. Open the SMIL file EPUBCheck names and find the audio element at the line it reports.
2. Correct the times from the audio file, or remove the par element if the phrase has no narration.
3. Rebuild the EPUB and run EPUBCheck again to confirm the message is gone.

## When it's not this

If clipBegin is later than clipEnd, the error is MED-008.

## Sources

- EPUB 3.3, §9.2.2.8 The audio element: https://www.w3.org/TR/epub-33/#sec-smil-audio-elem (read 2026-11-04)

Message text and severity: EPUBCheck (W3C, BSD-3-Clause). Explanation: EpubCC.