diff --git a/packages/ses/src/lockdown-shim.js b/packages/ses/src/lockdown-shim.js
index 7c63f0040c..068b72bff7 100644
--- a/packages/ses/src/lockdown-shim.js
+++ b/packages/ses/src/lockdown-shim.js
@@ -15,6 +15,7 @@
 import makeHardener from '@agoric/make-hardener';
 
 import { assert } from './assert.js';
+import { keys } from './commons.js';
 import { makeIntrinsicsCollector } from './intrinsics.js';
 import whitelistIntrinsics from './whitelist-intrinsics.js';
 import repairLegacyAccessors from './repair-legacy-accessors.js';
@@ -45,6 +46,8 @@ export const harden = ref => {
   return lockdownHarden(ref);
 };
 
+const alreadyHardenedIntrinsics = () => false;
+
 export function repairIntrinsics(options = {}) {
   // First time, absent options default to 'safe'.
   // Subsequent times, absent options default to first options.
@@ -72,15 +75,13 @@ export function repairIntrinsics(options = {}) {
 
   // Asserts for multiple invocation of lockdown().
   if (firstOptions) {
-    Object.keys(firstOptions).forEach(name => {
+    for (const name of keys(firstOptions)) {
       assert(
         options[name] === firstOptions[name],
         `lockdown(): cannot re-invoke with different option ${name}`,
       );
-    });
-    // Returning `false` indicates that lockdown() made no changes because it
-    // was invoked from SES with non-conflicting options.
-    return false;
+    }
+    return alreadyHardenedIntrinsics;
   }
 
   firstOptions = {
@@ -148,13 +149,11 @@ export function repairIntrinsics(options = {}) {
     // Returning `true` indicates that this is a JS to SES transition.
     return true;
   }
+
   return hardenIntrinsics;
 }
 
 export const lockdown = (options = {}) => {
-  const optHardenIntrinsics = repairIntrinsics(options);
-  if (optHardenIntrinsics === false) {
-    return false;
-  }
-  return optHardenIntrinsics();
+  const maybeHardenIntrinsics = repairIntrinsics(options);
+  return maybeHardenIntrinsics();
 };