diff --git a/packages/vats/src/core/core-eval-env.d.ts b/packages/vats/src/core/core-eval-env.d.ts
index 83b01732d40..a53028d74b5 100644
--- a/packages/vats/src/core/core-eval-env.d.ts
+++ b/packages/vats/src/core/core-eval-env.d.ts
@@ -29,6 +29,8 @@ declare global {
 
   // endowments
   var VatData: VatData;
+  // This is correctly the `Assert` type from `'ses'`, not from @endo/errors
+  // See https://github.com/Agoric/agoric-sdk/issues/9515
   var assert: Assert;
 
   // console is a VirtualConsole but this directive fails to override the extant global `console`