diff --git a/packages/patterns/src/types.js b/packages/patterns/src/types.js
index 3b300ba84e..bf803a9ee8 100644
--- a/packages/patterns/src/types.js
+++ b/packages/patterns/src/types.js
@@ -4,6 +4,7 @@ export {};
 
 /** @typedef {import('@endo/pass-style').Passable} Passable */
 /** @typedef {import('@endo/pass-style').PassStyle} PassStyle */
+/** @typedef {import('@endo/pass-style').RemotableObject} RemotableObject */
 /**
  * @template {string} [Tag=string]
  * @template {Passable} [Payload=Passable]
@@ -21,9 +22,8 @@ export {};
 /** @typedef {import('@endo/marshal').RankCompare} RankCompare */
 /** @typedef {import('@endo/marshal').RankCover} RankCover */
 
-// FIXME exclude nested Error and Promise
 /**
- * @typedef {Exclude<Passable, Error | Promise>} Key
+ * @typedef {import('@endo/pass-style').Passable<RemotableObject, never>} Key
  *
  * Keys are Passable arbitrarily-nested pass-by-copy containers
  * (CopyArray, CopyRecord, CopySet, CopyBag, CopyMap) in which every
diff --git a/packages/patterns/test/test-patterns.js b/packages/patterns/test/test-patterns.js
index 60a9891da1..031213b9f4 100644
--- a/packages/patterns/test/test-patterns.js
+++ b/packages/patterns/test/test-patterns.js
@@ -532,6 +532,7 @@ const runTests = (t, successCase, failCase) => {
     t.throws(
       () => {
         copyMapComparison || Fail`No CopyMap comparison support`;
+        // @ts-expect-error FIXME Key types
         successCase(specimen, M.gt(makeCopyMap([])));
       },
       { message: 'No CopyMap comparison support' },