diff -r c6a0b5b64133 -r 84920274cb32 vm/src/test/java/org/apidesign/vm4brwsr/StringTest.java
--- a/vm/src/test/java/org/apidesign/vm4brwsr/StringTest.java	Sun Nov 25 23:14:58 2012 +0100
+++ b/vm/src/test/java/org/apidesign/vm4brwsr/StringTest.java	Tue Nov 27 22:22:48 2012 +0100
@@ -68,6 +68,14 @@
         );
     }
 
+    @Test public void instanceOfWorks() throws Exception {
+        assertExec(
+            "It is string",
+            StringSample.class, "isStringInstanceZ",
+            Double.valueOf(1.0)
+        );
+    }
+
     @Test(timeOut=10000) public void toStringConcatenation() throws Exception {
         assertExec(
             "Five executions should generate 5Hello World!",