diff --git a/deno/lib/__tests__/transformer.test.ts b/deno/lib/__tests__/transformer.test.ts
index 5d7760780..9a1f92951 100644
--- a/deno/lib/__tests__/transformer.test.ts
+++ b/deno/lib/__tests__/transformer.test.ts
@@ -202,6 +202,7 @@ test("preprocess", () => {
 
   const value = schema.parse("asdf");
   expect(value).toEqual(["asdf"]);
+  util.assertEqual<typeof schema["_input"], unknown>(true);
 });
 
 test("async preprocess", async () => {
diff --git a/package.json b/package.json
index bb0235fce..72749e287 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "zod",
-  "version": "3.19.0",
+  "version": "3.19.1",
   "description": "TypeScript-first schema declaration and validation library with static type inference",
   "main": "./lib/index.js",
   "types": "./index.d.ts",
diff --git a/src/__tests__/transformer.test.ts b/src/__tests__/transformer.test.ts
index 45fba26a6..4af6117f3 100644
--- a/src/__tests__/transformer.test.ts
+++ b/src/__tests__/transformer.test.ts
@@ -201,6 +201,7 @@ test("preprocess", () => {
 
   const value = schema.parse("asdf");
   expect(value).toEqual(["asdf"]);
+  util.assertEqual<typeof schema["_input"], unknown>(true);
 });
 
 test("async preprocess", async () => {