A technique for detecting an encoder functionality issue in a media distribution system is presented. In the media distribution system consecutive media segments generated by an encoder are transmitted to a media client, and media descriptions describe expected availability times of media segments for the media client. A method implementation of the technique comprises the step of monitoring an availability time of a media segment compared to an expected availability time of the media segment, wherein the expected availability time is described by, or derived from, a media description. The method further comprises determining whether a deviation of the monitored availability time of the media segment from the expected availability time of the media segment is present, and detecting the encoder functionality issue based on a result of the determination. The encoder functionality issue may comprise one or more of an encoder restart, an encoder malfunction and an encoder time drift.