diff --git a/sign.js b/sign.js
index 82bf526..bd2a742 100644
--- a/sign.js
+++ b/sign.js
@@ -84,6 +84,10 @@ const options_for_objects = [
 ];
 
 module.exports = function (payload, secretOrPrivateKey, options, callback) {
+  if (typeof payload !== 'object') {
+    throw Error('Payload must be valid JSON object')
+  }
+  
   if (typeof options === 'function') {
     callback = options;
     options = {};
diff --git a/test/non_object_values.tests.js b/test/non_object_values.tests.js
index a3de4ea..4955b9d 100644
--- a/test/non_object_values.tests.js
+++ b/test/non_object_values.tests.js
@@ -3,16 +3,34 @@ var expect = require('chai').expect;
 
 describe('non_object_values values', function() {
 
-  it('should work with string', function () {
-    var token = jwt.sign('hello', '123');
-    var result = jwt.verify(token, '123');
-    expect(result).to.equal('hello');
+  it('should does not work with string', function () {
+    expect(function () {
+      jwt.sign('hello', '123');
+    }).to.throw('Payload must be valid JSON object');
   });
 
-  it('should work with number', function () {
-    var token = jwt.sign(123, '123');
-    var result = jwt.verify(token, '123');
-    expect(result).to.equal('123');
+  it('should does not work with number', function () {
+    expect(function () {
+      jwt.sign(123, '123');
+    }).to.throw('Payload must be valid JSON object');
   });
 
+  it('should does not work with function', function () {
+    expect(function () {
+      jwt.sign(function () { return 0 }, '123')
+    }).to.throw('Payload must be valid JSON object')
+  })
+
+  it('should does not work with boolean', function () {
+    expect(function () {
+      jwt.sign(true, '123')
+    }).to.throw('Payload must be valid JSON object')
+  })
+
+  it('should does not work with undefined', function () {
+    expect(function () {
+      jwt.sign(undefined, '123')
+    }).to.throw('Payload must be valid JSON object')
+  })
+
 });