Skew value for differential pair is wrong

I’m trying to length match a pair of traces using the Route > “Tune skew of a differential pair” tool. The tool has worked fine for about 6 pairs already on my PCB but is now producing strange skew values and interpreting the wrong track in the pair as the shortest. As an example, the lengths of my tracks HDMI0_D0_N (highlighted track) and HDMI0_D0_P (the track above the highlighted one) are 62.4240mm and 65.1077mm respectively but the skew value is 14.1054mm. Please see screenshot.

I must confess that I’m using a nightly build (5.99.0-8723-gf47e64c47d). Is this a bug perhaps?

First you should update to the latest nightly build.

Good point. Just updated to last night’s build but the issue is still there.

Sounds like a bug. Can you please report it with the board file to


Issue reported


It would be nice if KiCad could automatically cleanup a track as it’s laid out. Maybe consider there to be an implicit “draw head” that anchors any unfinished track and prevents its removal (as this would prevent drawing a trace in the first place).

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