diff --git a/compiler/forget/src/__tests__/fixtures/compiler/_bug.lambda-mutated-non-reactive-to-reactive.expect.md b/compiler/forget/src/__tests__/fixtures/compiler/_bug.lambda-mutated-non-reactive-to-reactive.expect.md
new file mode 100644
index 0000000000..a8f955e955
--- /dev/null
+++ b/compiler/forget/src/__tests__/fixtures/compiler/_bug.lambda-mutated-non-reactive-to-reactive.expect.md
@@ -0,0 +1,43 @@
+
+## Input
+
+```javascript
+function f(a) {
+  let x;
+  (() => {
+    x = { a };
+  })();
+  return <div x={x} />;
+}
+
+```
+
+## Code
+
+```javascript
+import { unstable_useMemoCache as useMemoCache } from "react";
+function f(a) {
+  const $ = useMemoCache(3);
+  const c_0 = $[0] !== a;
+  let x;
+  if (c_0) {
+    (() => {
+      x = { a };
+    })();
+    $[0] = a;
+    $[1] = x;
+  } else {
+    x = $[1];
+  }
+  let t0;
+  if ($[2] === Symbol.for("react.memo_cache_sentinel")) {
+    t0 = <div x={x} />;
+    $[2] = t0;
+  } else {
+    t0 = $[2];
+  }
+  return t0;
+}
+
+```
+      
\ No newline at end of file
diff --git a/compiler/forget/src/__tests__/fixtures/compiler/_bug.lambda-mutated-non-reactive-to-reactive.js b/compiler/forget/src/__tests__/fixtures/compiler/_bug.lambda-mutated-non-reactive-to-reactive.js
new file mode 100644
index 0000000000..85c905ea13
--- /dev/null
+++ b/compiler/forget/src/__tests__/fixtures/compiler/_bug.lambda-mutated-non-reactive-to-reactive.js
@@ -0,0 +1,7 @@
+function f(a) {
+  let x;
+  (() => {
+    x = { a };
+  })();
+  return <div x={x} />;
+}