diff --git a/doc/playground.md b/doc/playground.md
index 00151d2cd2..ccc5270db0 100644
--- a/doc/playground.md
+++ b/doc/playground.md
@@ -47,7 +47,7 @@ var obj = {};
 if (Object.prototype.hasOwnProperty.call(obj, "x")) obj.x = 2;
 ```
 
-### Method binding expression.
+### Method binding expression
 
 ```javascript
 var fn = obj:method;