diff --git a/src/lib/std.rc b/src/lib/std.rc
index fca67a25da4..ffbf26b5928 100644
--- a/src/lib/std.rc
+++ b/src/lib/std.rc
@@ -75,6 +75,7 @@ mod net;
 
 // FIXME: parametric
 mod map;
+mod treemap;
 mod deque;
 mod list;
 mod rand;
diff --git a/src/lib/treemap.rs b/src/lib/treemap.rs
new file mode 100644
index 00000000000..97ab1353c6b
--- /dev/null
+++ b/src/lib/treemap.rs
@@ -0,0 +1,76 @@
+/*
+A key,value store that works on anything.
+
+This works using a binary search tree. In the first version, it's a
+very naive algorithm, but it will probably be updated to be a
+red-black tree or something else.
+
+*/
+
+import option::some;
+import option::none;
+import option = option::t;
+
+export treemap;
+export init;
+export insert;
+export find;
+
+tag tree_node<@K, @V> {
+    empty;
+    node(@K, @V, treemap<K, V>, treemap<K, V>);
+}
+
+type treemap<@K, @V> = @mutable tree_node<K, V>;
+
+fn init<@K, @V>() -> treemap<K,V> { @mutable empty }
+
+fn insert<@K, @V>(m : &treemap<K, V>, k : &K, v : &V) {
+    alt m {
+      @empty. {
+        *m = node(@k, @v, @mutable empty, @mutable empty);
+      }
+      @node(@kk, _, _, _) {
+        // We have to name left and right individually, because
+        // otherwise the alias checker complains.
+        if k < kk {
+            alt m {
+              @node(_, _, left, _) {
+                insert(left, k, v);
+              }
+            }
+        }
+        else {
+            alt m {
+              @node(_, _, _, right) {
+                insert(right, k, v);
+              }
+            }
+        }
+      }
+    }
+}
+
+fn find<@K, @V>(m : &treemap<K, V>, k : &K) -> option<V> {
+  alt *m {
+    empty. { none }
+    node(@kk, @v, _, _) {
+      if k == kk { some(v) }
+      // Again, ugliness to unpack left and right individually.
+      else if k < kk {
+          alt *m {
+            node(_, _, left, _) {
+              find(left, k)
+            }
+          }
+      }
+      else {
+          alt *m {
+            node(_, _, _, right) {
+              find(right, k)
+            }
+          }
+      }
+    }
+  }
+}
diff --git a/src/test/stdtest/stdtest.rc b/src/test/stdtest/stdtest.rc
index ecf157cddae..64d52beb202 100644
--- a/src/test/stdtest/stdtest.rc
+++ b/src/test/stdtest/stdtest.rc
@@ -12,6 +12,7 @@ mod io;
 mod vec;
 mod list;
 mod map;
+mod treemap;
 mod net;
 mod option;
 mod os;
diff --git a/src/test/stdtest/treemap.rs b/src/test/stdtest/treemap.rs
new file mode 100644
index 00000000000..58777b2579c
--- /dev/null
+++ b/src/test/stdtest/treemap.rs
@@ -0,0 +1,42 @@
+use std;
+import std::treemap::*;
+import std::option::some;
+import std::option::none;
+
+#[test]
+fn init_treemap() {
+    let m = init::<int, int>();
+}
+
+#[test]
+fn insert_one() {
+    let m = init();
+    insert(m, 1, 2);
+}
+
+#[test]
+fn insert_two() {
+    let m = init();
+    insert(m, 1, 2);
+    insert(m, 3, 4);
+}
+
+#[test]
+fn insert_find() {
+    let m = init();
+    insert(m, 1, 2);
+    assert(find(m, 1) == some(2));
+}
+
+#[test]
+fn find_empty() {
+    let m = init::<int, int>();
+    assert(find(m, 1) == none);
+}
+
+#[test]
+fn find_not_found() {
+    let m = init();
+    insert(m, 1, 2);
+    assert(find(m, 2) == none);
+}