diff --git a/index.js b/index.js
index 82271f6..951a698 100644
--- a/index.js
+++ b/index.js
@@ -73,7 +73,7 @@ function createError () {
     deprecate('non-error status code; use only 4xx or 5xx status codes')
   }
 
-  if (typeof status !== 'number' ||
+  if (typeof status !== 'number' || isNaN(status) ||
     (!statuses.message[status] && (status < 400 || status >= 600))) {
     status = 500
   }
diff --git a/test/test.js b/test/test.js
index 7db9f16..dd337f5 100644
--- a/test/test.js
+++ b/test/test.js
@@ -331,6 +331,15 @@ describe('HTTP Errors', function () {
     assert.strictEqual(err.expose, false)
   })
 
+  it('createError(NaN) should default to 500', function () {
+    var err = createError(NaN)
+    assert.strictEqual(err.name, 'InternalServerError')
+    assert.strictEqual(err.message, 'Internal Server Error')
+    assert.strictEqual(err.status, 500)
+    assert.strictEqual(err.statusCode, 500)
+    assert.strictEqual(err.expose, false)
+  })
+
   it('createError(err, props)', function () {
     var _err = new Error('LOL')
     _err.status = 404