diff --git a/src/CHANGES.md b/src/CHANGES.md
index 15285f1157..d5b93d4a85 100644
--- a/src/CHANGES.md
+++ b/src/CHANGES.md
@@ -5,6 +5,7 @@
 -   \[FIX] Accidentally swapped Neuromag/Elekta/MEGIN cross-talk & fine-calibration filename extensions [#621](https://github.com/bids-standard/bids-specification/pull/621) ([hoechenberger](https://github.com/hoechenberger))
 -   \[INFRA] Move MRI section headings up a level [#618](https://github.com/bids-standard/bids-specification/pull/618) ([tsalo](https://github.com/tsalo))
 -   \[FIX] Change wrong text references from \*CoordinateSystemUnits to \*CoordinateUnits [#614](https://github.com/bids-standard/bids-specification/pull/614) ([sappelhoff](https://github.com/sappelhoff))
+-   \[ENH] Describe arbitrary units in Common Principles [#606](https://github.com/bids-standard/bids-specification/pull/606) ([tsalo](https://github.com/tsalo))
 -   \[FIX] Clarify data types and requirement levels for all JSON files [#605](https://github.com/bids-standard/bids-specification/pull/605) ([sappelhoff](https://github.com/sappelhoff))
 -   \[INFRA] downgrade github-changelog-generator to 1.14.3 due to issue with 1.15.2 [#600](https://github.com/bids-standard/bids-specification/pull/600) ([sappelhoff](https://github.com/sappelhoff))
 -   \[FIX] tighter rules for sharing MEG cross-talk and fine-calibration .fif files [#598](https://github.com/bids-standard/bids-specification/pull/598) ([sappelhoff](https://github.com/sappelhoff))