diff --git a/packages/express-wrapper/src/middleware.ts b/packages/express-wrapper/src/middleware.ts
index 947760f7..38fd12e3 100644
--- a/packages/express-wrapper/src/middleware.ts
+++ b/packages/express-wrapper/src/middleware.ts
@@ -216,5 +216,5 @@ export async function runMiddlewareChainIgnoringResults<
       }
     });
   }
-  return input;
+  return { ...input, ...(req.body || {}) };
 }
diff --git a/packages/express-wrapper/test/middleware.test.ts b/packages/express-wrapper/test/middleware.test.ts
index 397f4e03..938b3938 100644
--- a/packages/express-wrapper/test/middleware.test.ts
+++ b/packages/express-wrapper/test/middleware.test.ts
@@ -40,6 +40,38 @@ test('should handle errors passed to next()', async () => {
   );
 });
 
+test('middleware that modifies req should pass changes through chain', async () => {
+  const testReq = { body: {}, headers: {} } as express.Request;
+  const testRes = {} as express.Response;
+
+  const modifyReqMiddleware: express.RequestHandler = (req, _res, next) => {
+    (req as any).userId = 123;
+    next();
+  };
+
+  const checkReqMiddleware: express.RequestHandler = (req, _res, next) => {
+    assert.equal(
+      (req as any).userId,
+      123,
+      'userId should still be on req in second middleware',
+    );
+    next();
+  };
+
+  await runMiddlewareChain(
+    { foo: 'test' },
+    [modifyReqMiddleware, noopMiddleware, checkReqMiddleware],
+    testReq,
+    testRes,
+  );
+
+  assert.equal(
+    (testReq as any).userId,
+    123,
+    'req should still have userId after chain',
+  );
+});
+
 test('should work with middleware that return values', async () => {
   const result = await runMiddlewareChain(
     { foo: 'test' },
diff --git a/packages/express-wrapper/test/server.test.ts b/packages/express-wrapper/test/server.test.ts
index 03461f2e..5dd06366 100644
--- a/packages/express-wrapper/test/server.test.ts
+++ b/packages/express-wrapper/test/server.test.ts
@@ -276,3 +276,59 @@ test('should return a 400 when request fails to decode', async () => {
 
   assert(response.body.error.startsWith('Invalid value undefined supplied to'));
 });
+
+test('middleware that modifies req.body should reach handler even without routeHandler()', async () => {
+  const PostWithData = httpRoute({
+    path: '/data',
+    method: 'POST',
+    request: httpRequest({
+      body: {
+        originalField: t.string,
+        addedByMiddleware: optional(t.string),
+      },
+    }),
+    response: {
+      200: t.type({
+        originalField: t.string,
+        addedByMiddleware: optional(t.string),
+      }),
+    },
+  });
+
+  const testApiSpec = apiSpec({
+    'test.route': {
+      post: PostWithData,
+    },
+  });
+
+  const modifyBodyMiddleware: express.RequestHandler = (req, _res, next) => {
+    req.body.addedByMiddleware = 'ADDED';
+    next();
+  };
+
+  const handler = async (params: { originalField: string; addedByMiddleware?: string }) => {
+    return {
+      type: 200,
+      payload: {
+        originalField: params.originalField,
+        addedByMiddleware: params.addedByMiddleware,
+      },
+    } as const;
+  };
+
+  const app = createServer(testApiSpec, (app: express.Application) => {
+    app.use(express.json());
+    return {
+      'test.route': {
+        post: { middleware: [modifyBodyMiddleware], handler },
+      },
+    };
+  });
+
+  const response = await supertest(app)
+    .post('/data')
+    .send({ originalField: 'test' })
+    .expect(200);
+
+  assert.equal(response.body.addedByMiddleware, 'ADDED', 'addedByMiddleware should be present because req.body is part of req.decoded');
+});