diff --git a/src/structs/coercions.ts b/src/structs/coercions.ts
index 62566c50..ee2f8d10 100644
--- a/src/structs/coercions.ts
+++ b/src/structs/coercions.ts
@@ -43,7 +43,14 @@ export function defaulted<T, S>(
   } = {}
 ): Struct<T, S> {
   return coerce(struct, unknown(), (x) => {
-    const f = typeof fallback === 'function' ? fallback() : fallback
+    // To avoid a pass-by-reference bug, we'll clone objects when encountered
+    // here, but the for performance avoid cloning primatives and functions
+    const f =
+      typeof fallback === 'function'
+        ? fallback()
+        : typeof fallback === 'object'
+          ? structuredClone(fallback)
+          : fallback
 
     if (x === undefined) {
       return f
diff --git a/test/defaultedRecord.test.ts b/test/defaultedRecord.test.ts
new file mode 100644
index 00000000..1acf5f98
--- /dev/null
+++ b/test/defaultedRecord.test.ts
@@ -0,0 +1,26 @@
+import { expect, test } from 'vitest'
+import { create, defaulted, record, string } from '../src'
+
+test('Defaulted record value is an empty object', () => {
+  const DefaultedRecord = defaulted(record(string(), string()), {})
+
+  const recordA = create(undefined, DefaultedRecord)
+  const recordB = create(undefined, DefaultedRecord)
+
+  // Shouldn't change recordB
+  recordA.name = 'maddy'
+
+  expect(recordB.name).toBeUndefined()
+})
+
+test('Defaulted record value is an empty object returned by a function', () => {
+  const DefaultedRecordFn = defaulted(record(string(), string()), () => ({}))
+
+  const recordA = create(undefined, DefaultedRecordFn)
+  const recordB = create(undefined, DefaultedRecordFn)
+
+  // Shouldn't change recordB
+  recordA.name = 'george'
+
+  expect(recordB.name).toBeUndefined()
+})