diff --git a/src/lib/int.rs b/src/lib/int.rs
index fe7689e3e2872..4b420d96c27a2 100644
--- a/src/lib/int.rs
+++ b/src/lib/int.rs
@@ -1,3 +1,10 @@
+fn max_value() -> int {
+  ret min_value() - 1;
+}
+
+fn min_value() -> int {
+  ret (-1 << (sys::size_of::<int>()  * 8u as int - 1)) as int;
+}
 
 
 pure fn add(x: int, y: int) -> int { ret x + y; }
diff --git a/src/lib/rand.rs b/src/lib/rand.rs
index fee8bbe06baec..b4e5ebc3058ff 100644
--- a/src/lib/rand.rs
+++ b/src/lib/rand.rs
@@ -14,6 +14,7 @@ native "rust" mod rustrt {
 type rng =
     obj {
         fn next() -> u32;
+        fn next_float() -> float;
     };
 
 resource rand_res(c: rustrt::rctx) { rustrt::rand_free(c); }
@@ -21,6 +22,13 @@ resource rand_res(c: rustrt::rctx) { rustrt::rand_free(c); }
 fn mk_rng() -> rng {
     obj rt_rng(c: @rand_res) {
         fn next() -> u32 { ret rustrt::rand_next(**c); }
+        fn next_float() -> float {
+          let u1 = rustrt::rand_next(**c) as float;
+          let u2 = rustrt::rand_next(**c) as float;
+          let u3 = rustrt::rand_next(**c) as float;
+          let scale = u32::max_value() as float;
+          ret ((u1 / scale + u2) / scale + u3) / scale;
+        }
     }
     ret rt_rng(@rand_res(rustrt::rand_new()));
 }
diff --git a/src/lib/std.rc b/src/lib/std.rc
index 94f5906460991..2e65c7503a958 100644
--- a/src/lib/std.rc
+++ b/src/lib/std.rc
@@ -13,6 +13,7 @@ mod char;
 mod int;
 mod uint;
 mod u8;
+mod u32;
 mod u64;
 mod vec;
 mod str;
diff --git a/src/lib/u32.rs b/src/lib/u32.rs
new file mode 100644
index 0000000000000..de368fff9d81a
--- /dev/null
+++ b/src/lib/u32.rs
@@ -0,0 +1,13 @@
+pure fn max_value() -> u32 { ret 4294967296u32; }
+pure fn min_value() -> u32 { ret 0u32; }
+
+//
+// Local Variables:
+// mode: rust
+// fill-column: 78;
+// indent-tabs-mode: nil
+// c-basic-offset: 4
+// buffer-file-coding-system: utf-8-unix
+// compile-command: "make -k -C $RBUILD 2>&1 | sed -e 's/\\/x\\//x:\\//g'";
+// End:
+//
diff --git a/src/lib/u64.rs b/src/lib/u64.rs
index 8082f7aef0d52..497b60acdbf09 100644
--- a/src/lib/u64.rs
+++ b/src/lib/u64.rs
@@ -1,3 +1,6 @@
+pure fn max_value() -> u64 { ret 18446744073709551615u64; }
+pure fn min_value() -> u64 { ret 0u64; }
+
 fn to_str(n: u64, radix: uint) -> str {
     assert (0u < radix && radix <= 16u);
 
diff --git a/src/lib/u8.rs b/src/lib/u8.rs
index 5dea03b0bdd19..d70cb8a4f8319 100644
--- a/src/lib/u8.rs
+++ b/src/lib/u8.rs
@@ -1,4 +1,5 @@
-
+pure fn max_value() -> u8 { ret 255u8; }
+pure fn min_value() -> u8 { ret 0u8; }
 
 pure fn add(x: u8, y: u8) -> u8 { ret x + y; }
 
diff --git a/src/lib/uint.rs b/src/lib/uint.rs
index 12a512e1de829..84b6bc5b1e07e 100644
--- a/src/lib/uint.rs
+++ b/src/lib/uint.rs
@@ -1,4 +1,18 @@
-
+/**
+ * Return the minimal value for an uint.
+ *
+ * This is always 0
+ */
+pure fn min_value() -> uint { ret 0u; }
+
+/**
+ * Return the maximal value for an uint.
+ *
+ * This is 2^wordsize - 1
+ */
+pure fn max_value() -> uint {
+     ret 0u - 1u;
+}
 
 fn add(x: uint, y: uint) -> uint { ret x + y; }
 
diff --git a/src/test/stdtest/int.rs b/src/test/stdtest/int.rs
index 61d3448a175e9..4a87908e5a64f 100644
--- a/src/test/stdtest/int.rs
+++ b/src/test/stdtest/int.rs
@@ -23,3 +23,10 @@ fn test_pow() {
     assert (int::pow(-3, 3u) == -27);
     assert (int::pow(4, 9u) == 262144);
 }
+
+#[test]
+fn test_overflows() {
+   assert (int::max_value() > 0);
+   assert (int::min_value() <= 0);
+   assert (int::min_value() + int::max_value() + 1 == 0);
+}
\ No newline at end of file
diff --git a/src/test/stdtest/uint.rs b/src/test/stdtest/uint.rs
index 7361c76b70bbb..141b59ace82a8 100644
--- a/src/test/stdtest/uint.rs
+++ b/src/test/stdtest/uint.rs
@@ -47,3 +47,10 @@ fn test_next_power_of_two() {
     assert (uint::next_power_of_two(38u) == 64u);
     assert (uint::next_power_of_two(39u) == 64u);
 }
+
+#[test]
+fn test_overflows() {
+   assert (uint::max_value() > 0u);
+   assert (uint::min_value() <= 0u);
+   assert (uint::min_value() + uint::max_value() + 1u == 0u);
+}
\ No newline at end of file