diff --git a/deno/lib/__tests__/object.test.ts b/deno/lib/__tests__/object.test.ts
index e7ea349ab..fac2b9ffd 100644
--- a/deno/lib/__tests__/object.test.ts
+++ b/deno/lib/__tests__/object.test.ts
@@ -293,3 +293,18 @@ test("intersection of object with refine with date", async () => {
   const result = await schema.parseAsync({ a: new Date(1637353595983) });
   expect(result).toEqual({ a: new Date(1637353595983) });
 });
+
+test("constructor key", () => {
+  const person = z
+    .object({
+      name: z.string(),
+    })
+    .strict();
+
+  expect(() =>
+    person.parse({
+      name: "bob dylan",
+      constructor: 61,
+    })
+  ).toThrow();
+});
diff --git a/deno/lib/types.ts b/deno/lib/types.ts
index a9a3c0b8f..a71a8346e 100644
--- a/deno/lib/types.ts
+++ b/deno/lib/types.ts
@@ -1499,7 +1499,7 @@ export class ZodObject<
 
     const { shape, keys: shapeKeys } = this._getCached();
     const dataKeys = util.objectKeys(ctx.data);
-    const extraKeys = dataKeys.filter((k) => !(k in shape));
+    const extraKeys = dataKeys.filter((k) => !shapeKeys.includes(k));
 
     const pairs: {
       key: ParseReturnType<any>;
diff --git a/package.json b/package.json
index 3eca7dbfd..872839608 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "zod",
-  "version": "3.12.1",
+  "version": "3.12.2",
   "description": "TypeScript-first schema declaration and validation library with static type inference",
   "main": "./lib/index.js",
   "types": "./lib/index.d.ts",
diff --git a/src/__tests__/object.test.ts b/src/__tests__/object.test.ts
index 3512c3879..fc01e6397 100644
--- a/src/__tests__/object.test.ts
+++ b/src/__tests__/object.test.ts
@@ -292,3 +292,18 @@ test("intersection of object with refine with date", async () => {
   const result = await schema.parseAsync({ a: new Date(1637353595983) });
   expect(result).toEqual({ a: new Date(1637353595983) });
 });
+
+test("constructor key", () => {
+  const person = z
+    .object({
+      name: z.string(),
+    })
+    .strict();
+
+  expect(() =>
+    person.parse({
+      name: "bob dylan",
+      constructor: 61,
+    })
+  ).toThrow();
+});
diff --git a/src/types.ts b/src/types.ts
index 6f9e8455d..4fea82f45 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -1499,7 +1499,7 @@ export class ZodObject<
 
     const { shape, keys: shapeKeys } = this._getCached();
     const dataKeys = util.objectKeys(ctx.data);
-    const extraKeys = dataKeys.filter((k) => !(k in shape));
+    const extraKeys = dataKeys.filter((k) => !shapeKeys.includes(k));
 
     const pairs: {
       key: ParseReturnType<any>;