diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3411789..49e7973 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,8 @@ and this project adheres to
 
 - CI: bump actions/checkout from 4 to 6 ([6c9eecd], [#49])
 - Bump ruff dev dependency from `^0.14.14` to `>=0.14.14,<0.16.0` ([ac8a1db], [#50])
+- Bump isort dev dependency from `^7.0.0` to `>=7,<9` to allow isort 8.x
+  ([4464bfd], [#51])
 
 ## [1.4.0] - 2026-02-09
 
@@ -160,6 +162,7 @@ and this project adheres to
 
 [6c9eecd]: https://github.com/LeakIX/l9format-python/commit/6c9eecd
 [ac8a1db]: https://github.com/LeakIX/l9format-python/commit/ac8a1db
+[4464bfd]: https://github.com/LeakIX/l9format-python/commit/4464bfd
 [ac4744e]: https://github.com/LeakIX/l9format-python/commit/ac4744e
 [d554f1e]: https://github.com/LeakIX/l9format-python/commit/d554f1e
 [7f49ff5]: https://github.com/LeakIX/l9format-python/commit/7f49ff5
@@ -246,3 +249,4 @@ and this project adheres to
 [#49]: https://github.com/LeakIX/l9format-python/pull/49
 [#50]: https://github.com/LeakIX/l9format-python/pull/50
 [#43]: https://github.com/LeakIX/l9format-python/issues/43
+[#51]: https://github.com/LeakIX/l9format-python/pull/51
diff --git a/pyproject.toml b/pyproject.toml
index 3c7ae68..3f58127 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -17,7 +17,7 @@ serde = "^0.9.0"
 [tool.poetry.group.dev.dependencies]
 black = "^26.1.0"
 fire = "^0.7.1"
-isort = "^7.0.0"
+isort = ">=7,<9"
 mypy = "^1.19.0"
 pip-audit = "^2.10.0"
 pytest = "^9.0.2"