diff --git a/types/mustache/mustache-tests.ts b/types/mustache/mustache-tests.ts
index ad9c410d76..30c920a30a 100644
--- a/types/mustache/mustache-tests.ts
+++ b/types/mustache/mustache-tests.ts
@@ -12,3 +12,18 @@ var output2 = Mustache.render(template2, view2);
 var view3 = { firstName: "John", lastName: "Smith", blogURL: "http://testblog.com" };
 var template3 = "<h1>{{firstName}} {{lastName}}</h1>Blog: {{blogURL}}";
 var html = Mustache.to_html(template3, view3);
+
+var view4 = new class extends Mustache.Context
+{
+    constructor()
+    {
+        super({});
+    }
+
+    public lookup(name: string)
+    {
+        return name.toUpperCase();
+    }
+};
+var template4 = "Hello, {{firstName}} {{lastName}}";
+var html4 = Mustache.render(template4, view4);
\ No newline at end of file