diff --git a/deno/lib/__tests__/object.test.ts b/deno/lib/__tests__/object.test.ts
index fac2b9ffd1..1bd290c14c 100644
--- a/deno/lib/__tests__/object.test.ts
+++ b/deno/lib/__tests__/object.test.ts
@@ -216,6 +216,28 @@ test("test inferred merged type", async () => {
   f1;
 });
 
+test("inferred merged types with optionals", async () => {
+  const Merged = z
+    .object({ a: z.string(), b: z.string().optional() })
+    .merge(z.object({ a: z.string().optional(), b: z.string() }));
+  type Merged = z.infer<typeof Merged>;
+  const f1: util.AssertEqual<Merged, { a?: string; b: string }> = true;
+  f1;
+});
+
+test("inferred unioned types with optionals", async () => {
+  const Unioned = z.union([
+    z.object({ a: z.string(), b: z.string().optional() }),
+    z.object({ a: z.string().optional(), b: z.string() }),
+  ]);
+  type Unioned = z.infer<typeof Unioned>;
+  const f1: util.AssertEqual<
+    Unioned,
+    { a: string; b?: string } | { a?: string; b: string }
+  > = true;
+  f1;
+});
+
 test("inferred type for unknown/any keys", () => {
   const myType = z.object({
     anyOptional: z.any().optional(),
diff --git a/src/__tests__/object.test.ts b/src/__tests__/object.test.ts
index fc01e6397d..3e0ecfc632 100644
--- a/src/__tests__/object.test.ts
+++ b/src/__tests__/object.test.ts
@@ -215,6 +215,28 @@ test("test inferred merged type", async () => {
   f1;
 });
 
+test("inferred merged types with optionals", async () => {
+  const Merged = z
+    .object({ a: z.string(), b: z.string().optional() })
+    .merge(z.object({ a: z.string().optional(), b: z.string() }));
+  type Merged = z.infer<typeof Merged>;
+  const f1: util.AssertEqual<Merged, { a?: string; b: string }> = true;
+  f1;
+});
+
+test("inferred unioned types with optionals", async () => {
+  const Unioned = z.union([
+    z.object({ a: z.string(), b: z.string().optional() }),
+    z.object({ a: z.string().optional(), b: z.string() }),
+  ]);
+  type Unioned = z.infer<typeof Unioned>;
+  const f1: util.AssertEqual<
+    Unioned,
+    { a: string; b?: string } | { a?: string; b: string }
+  > = true;
+  f1;
+});
+
 test("inferred type for unknown/any keys", () => {
   const myType = z.object({
     anyOptional: z.any().optional(),