diff --git a/src/test/run-pass/nullable-pointer-iotareduction.rs b/src/test/run-pass/nullable-pointer-iotareduction.rs
new file mode 100644
index 00000000000..0c4d297403c
--- /dev/null
+++ b/src/test/run-pass/nullable-pointer-iotareduction.rs
@@ -0,0 +1,87 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use core::{option, cast};
+
+// Iota-reduction is a rule in the Calculus of (Co-)Inductive Constructions,
+// which "says that a destructor applied to an object built from a constructor
+// behaves as expected".  -- http://coq.inria.fr/doc/Reference-Manual006.html
+//
+// It's a little more complicated here, because of pointers and regions and
+// trying to get assert failure messages that at least identify which case
+// failed.
+
+enum E<T> { Thing(int, T), Nothing((), ((), ()), [i8, ..0]) }
+impl<T> E<T> {
+    fn is_none(&self) -> bool { 
+        match *self {
+            Thing(*) => false,
+            Nothing(*) => true
+        }
+    }
+    fn get_ref<'r>(&'r self) -> (int, &'r T) {
+        match *self {
+            Nothing(*) => fail!(fmt!("E::get_ref(Nothing::<%s>)",  stringify!($T))),
+            Thing(x, ref y) => (x, y)
+        }
+    }
+}
+
+macro_rules! check_option {
+    ($e:expr: $T:ty) => {{
+        // FIXME #6000: remove the copy
+        check_option!(copy $e: $T, |ptr| assert!(*ptr == $e));
+    }};
+    ($e:expr: $T:ty, |$v:ident| $chk:expr) => {{
+        assert!(option::None::<$T>.is_none());
+        let s_ = option::Some::<$T>($e);
+        let $v = s_.get_ref();
+        $chk
+    }}
+}
+
+macro_rules! check_fancy {
+    ($e:expr: $T:ty) => {{
+        // FIXME #6000: remove the copy
+        check_fancy!(copy $e: $T, |ptr| assert!(*ptr == $e));
+    }};
+    ($e:expr: $T:ty, |$v:ident| $chk:expr) => {{
+        assert!(Nothing::<$T>((), ((), ()), [23i8, ..0]).is_none());
+        let t_ = Thing::<$T>(23, $e);
+        match t_.get_ref() {
+            (23, $v) => { $chk }
+            _ => fail!(fmt!("Thing::<%s>(23, %s).get_ref() != (23, _)",
+                            stringify!($T), stringify!($e)))
+        }
+    }}
+}
+
+macro_rules! check_type {
+    ($($a:tt)*) => {{
+        check_option!($($a)*);
+        check_fancy!($($a)*);
+    }}
+}
+
+pub fn main() {
+    check_type!(&17: &int);
+    check_type!(~18: ~int);
+    check_type!(@19: @int);
+    check_type!(~"foo": ~str);
+    check_type!(@"bar": @str);
+    check_type!(~[]: ~[int]);
+    check_type!(~[20, 22]: ~[int]);
+    check_type!(@[]: @[int]);
+    check_type!(@[24, 26]: @[int]);
+    let mint: uint = unsafe { cast::transmute(main) };
+    check_type!(main: extern fn(), |pthing| {
+        assert!(mint == unsafe { cast::transmute(*pthing) })
+    });
+}
diff --git a/src/test/run-pass/nullable-pointer-size.rs b/src/test/run-pass/nullable-pointer-size.rs
new file mode 100644
index 00000000000..246fc4e304d
--- /dev/null
+++ b/src/test/run-pass/nullable-pointer-size.rs
@@ -0,0 +1,44 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+enum E<T> { Thing(int, T), Nothing((), ((), ()), [i8, ..0]) }
+struct S<T>(int, T);
+
+// These are macros so we get useful assert messages.
+
+macro_rules! check_option {
+    ($T:ty) => {
+        assert!(sys::size_of::<Option<$T>>() == sys::size_of::<$T>());
+    }
+}
+
+macro_rules! check_fancy {
+    ($T:ty) => {
+        assert!(sys::size_of::<E<$T>>() == sys::size_of::<S<$T>>());
+    }
+}
+
+macro_rules! check_type {
+    ($T:ty) => {{
+        check_option!($T);
+        check_fancy!($T);
+    }}
+}
+
+pub fn main() {
+    check_type!(&'static int);
+    check_type!(~int);
+    check_type!(@int);
+    check_type!(~str);
+    check_type!(@str);
+    check_type!(~[int]);
+    check_type!(@[int]);
+    check_type!(extern fn());
+}