Simple immutable example doesn't work - why???

[Louis Berube]

Edit for (hopefully) better readability:

Simple example:

// file immutable_example.d

immutable class Test
{
     public:
         this(in uint value)
         {
             this.value = value;
         }
         unittest
         {
             auto t = new Test(4); // "Error: immutable method
                                   // immutable_example.Test.this
                                   // is not callable using
                                   // a mutable object"
             assert (t.value == 4);
         }
     private:
         uint value;
}

Assuming this is not a compiler issue, what am I missing?
Integer literal is about as immutable as it gets.