diff --git a/README.md b/README.md
index c7ae1ed..24acfed 100644
--- a/README.md
+++ b/README.md
@@ -34,16 +34,16 @@ srs({length: 256}, function(err, sr) {
 	console.log(sr);
 });
 ```
-### Options: alphabetic
+### Options: alphanumeric
 
-Optionally, you can specify a 'alphabetic' option to get a alphabetical chars only.
+Optionally, you can specify a 'alphanumeric' option to get a alphanumerical chars only.
 
 ```javascript
 // sync
-var result = srs({alphabetic: true});
+var result = srs({alphanumeric: true});
 
 // async
-srs({alphabetic: true}, function(err, sr) {
+srs({alphanumeric: true}, function(err, sr) {
 	console.log(sr);
 });
 ```
diff --git a/tests.js b/tests.js
index 630ba62..fa27e1a 100644
--- a/tests.js
+++ b/tests.js
@@ -50,7 +50,12 @@ srs({length: 256}, function(err, sr) {
 	);
 });
 
-
+srs({alphanumeric: true}, function(err, sr) {;
+	test('Must contain alphanumeric only',
+		sr.match(/^[a-zA-Z0-9_]*$/g)[0] === sr,
+		true
+	);
+});
 // sync tests
 test('generate a random string 32 chars long (sync)', srs().length, 32);
 test('generate a random string 1 chars long (sync)', srs({length:1}).length, 1);