diff --git a/packages/swingset-liveslots/test/watch-promise.test.js b/packages/swingset-liveslots/test/watch-promise.test.js
new file mode 100644
index 00000000000..52c4d033599
--- /dev/null
+++ b/packages/swingset-liveslots/test/watch-promise.test.js
@@ -0,0 +1,42 @@
+import test from 'ava';
+
+import { Far } from '@endo/marshal';
+import { makePromiseKit } from '@endo/promise-kit';
+import { setupTestLiveslots } from './liveslots-helpers.js';
+
+const build = vatPowers => {
+  const { VatData } = vatPowers;
+  const { makeKindHandle, defineDurableKind, watchPromise } = VatData;
+
+  const kh = makeKindHandle('handler');
+  const init = () => ({});
+  const behavior = {
+    onFulfilled: _value => 0,
+    onRejected: _reason => 0,
+  };
+  const makeHandler = defineDurableKind(kh, init, behavior);
+
+  return Far('root', {
+    async run() {
+      const pr = makePromiseKit();
+      const handler = makeHandler();
+      watchPromise(pr.promise, handler);
+      pr.resolve('ignored');
+    },
+  });
+};
+
+test.failing('watched local promises should not leak slotToVal entries', async t => {
+  const { dispatchMessage, testHooks } = await setupTestLiveslots(
+    t,
+    build,
+    'vatA',
+  );
+  const { slotToVal } = testHooks;
+  const initial = slotToVal.size;
+
+  await dispatchMessage('run');
+  t.is(slotToVal.size, initial);
+  await dispatchMessage('run');
+  t.is(slotToVal.size, initial);
+});