diff --git a/dev-notes.md b/dev-notes.md
index 20d6f6a..de62093 100644
--- a/dev-notes.md
+++ b/dev-notes.md
@@ -14,3 +14,8 @@ More info: <https://web.archive.org/web/20231127084426/https://firefox-source-do
 
 Consider using `PWDEBUG=1` (or `make test-debug`) when debugging the playwright
 test code.
+
+MSPV:
+    - 3.10
+        - Replace `t.Union` with `|`
+        - several places that match would work well