diff --git a/src/lib/task.rs b/src/lib/task.rs
index f15bdade360..90885f2ab46 100644
--- a/src/lib/task.rs
+++ b/src/lib/task.rs
@@ -2,6 +2,7 @@ native "rust" mod rustrt {
     fn task_sleep(uint time_in_us);
     fn task_yield();
     fn task_join(task t);
+    fn task_unsupervise();
     fn pin_task();
     fn unpin_task();
 }
@@ -23,6 +24,10 @@ fn join(task t) {
     ret rustrt::task_join(t);
 }
 
+fn unsupervise() {
+    ret rustrt::task_unsupervise();
+}
+
 fn pin() {
     rustrt::pin_task();
 }
diff --git a/src/rt/rust_builtin.cpp b/src/rt/rust_builtin.cpp
index 1ed2c4ec36d..e8900dd730a 100644
--- a/src/rt/rust_builtin.cpp
+++ b/src/rt/rust_builtin.cpp
@@ -425,6 +425,11 @@ task_join(rust_task *task, rust_task *join_task) {
     }
 }
 
+extern "C" CDECL void
+task_unsupervise(rust_task *task) {
+    task->unsupervise();
+}
+
 /* Debug builtins for std.dbg. */
 
 static void