diff --git a/lib/response.js b/lib/response.js
index 7a2f0ecce56..5a07b137099 100644
--- a/lib/response.js
+++ b/lib/response.js
@@ -326,11 +326,14 @@ res.jsonp = function jsonp(obj) {
  */
 
 res.sendStatus = function sendStatus(statusCode) {
-  var body = statuses.message[statusCode] || String(statusCode)
-
+  // Emit deprecation warning for invalid status codes
+  if (typeof statusCode !== 'number') {
+    deprecate('Invalid status code: ' + String(statusCode) + '. Status code must be a number. This will throw an error in Express 6.');
+    statusCode = 500;
+  }
+  var body = statuses.message[statusCode] || String(statusCode);
   this.status(statusCode);
   this.type('txt');
-
   return this.send(body);
 };
 
diff --git a/test/res.sendStatus.js b/test/res.sendStatus.js
index b244cf9d173..280ab883fa6 100644
--- a/test/res.sendStatus.js
+++ b/test/res.sendStatus.js
@@ -1,4 +1,4 @@
-'use strict'
+'use strict'
 
 var express = require('..')
 var request = require('supertest')
@@ -29,16 +29,79 @@ describe('res', function () {
       .expect(599, '599', done);
     })
 
-    it('should raise error for invalid status code', function (done) {
+    describe('with invalid status codes', function(){
+      it('should fallback to 500 for undefined status code', function(done){
+        var app = express()
+
+        app.use(function(req, res){
+          res.sendStatus(undefined)
+        })
+
+        request(app)
+          .get('/')
+          .expect(500, 'Internal Server Error', done)
+      })
+
+      it('should fallback to 500 for BigInt status code', function(done){
+        var app = express()
+
+        app.use(function(req, res){
+          res.sendStatus(200n)
+        })
+
+        request(app)
+          .get('/')
+          .expect(500, 'Internal Server Error', done)
+      })
+
+      it('should fallback to 500 for string status code', function(done){
+        var app = express()
+
+        app.use(function(req, res){
+          res.sendStatus('invalid')
+        })
+
+        request(app)
+          .get('/')
+          .expect(500, 'Internal Server Error', done)
+      })
+
+      it('should contain deprecation logic for invalid status codes', function(){
+        // Test that the deprecation logic is present by examining the function
+        var express = require('..')
+        var app = express()
+        var res = app.response
+
+        // Verify the function contains deprecation logic
+        var sendStatusSource = res.sendStatus.toString()
+        // Check that the function contains the deprecation warning
+        if (sendStatusSource.indexOf('deprecate') === -1) {
+          throw new Error('sendStatus function should contain deprecation warning')
+        }
+        if (sendStatusSource.indexOf('typeof statusCode !== \'number\'') === -1) {
+          throw new Error('sendStatus function should check for non-number status codes')
+        }
+        if (sendStatusSource.indexOf('statusCode = 500') === -1) {
+          throw new Error('sendStatus function should fallback to status 500')
+        }
+
+        // Check deprecation message content
+        if (sendStatusSource.indexOf('Express 6') === -1) {
+          throw new Error('Deprecation message should mention Express 6')
+        }
+      })
+    })
+
+    it('should not affect valid number status codes', function(done){
       var app = express()
 
-      app.use(function (req, res) {
-        res.sendStatus(undefined).end()
+      app.use(function(req, res){
+        res.sendStatus(200)
       })
 
       request(app)
         .get('/')
-        .expect(500, /TypeError: Invalid status code/, done)
+        .expect(200, 'OK', done)
     })
   })
 })