diff --git a/plans/apl-on-sx.md b/plans/apl-on-sx.md
index de380cf4..b181f7bd 100644
--- a/plans/apl-on-sx.md
+++ b/plans/apl-on-sx.md
@@ -83,7 +83,7 @@ Core mapping:
 - [x] Power `f⍣n` — apply f n times; `f⍣≡` until fixed point
 - [x] Rank `f⍤k` — apply f at sub-rank k
 - [x] At `@` — selective replace
-- [ ] 40+ tests in `lib/apl/tests/operators.sx`
+- [x] 40+ tests in `lib/apl/tests/operators.sx`
 
 ### Phase 5 — dfns + tradfns + control flow
 - [ ] Dfn `{…}` with `⍺` (left arg, may be absent → niladic/monadic), `⍵` (right arg), `∇` (recurse), guards `cond:expr`, default left arg `⍺←default`