diff --git a/src/lib/sys.rs b/src/lib/sys.rs
index 0eafc5eec29..18e2d3261c7 100644
--- a/src/lib/sys.rs
+++ b/src/lib/sys.rs
@@ -17,5 +17,6 @@
   fn align_of[T]() -> uint;
   fn refcount[T](@T t) -> uint;
   fn gc();
+  fn unsupervise();
 }
 
diff --git a/src/rt/rust_builtin.cpp b/src/rt/rust_builtin.cpp
index 091ba9c9a35..339452c5129 100644
--- a/src/rt/rust_builtin.cpp
+++ b/src/rt/rust_builtin.cpp
@@ -86,6 +86,11 @@ gc(rust_task *task) {
     task->gc(1);
 }
 
+extern "C" CDECL void
+unsupervise(rust_task *task) {
+    task->unsupervise();
+}
+
 extern "C" CDECL rust_vec*
 vec_alloc(rust_task *task, type_desc *t, size_t n_elts)
 {
diff --git a/src/rt/rust_internal.h b/src/rt/rust_internal.h
index fafc1924a55..f877cefc71d 100644
--- a/src/rt/rust_internal.h
+++ b/src/rt/rust_internal.h
@@ -625,7 +625,7 @@ rust_task : public rc_base<rust_task>,
     ptr_vec<rust_task> *state;
     rust_cond *cond;
     uintptr_t* dptr;           // Rendezvous pointer for send/recv.
-    rust_task *spawner;        // Parent-link.
+    rust_task *supervisor;     // Parent-link for failure propagation.
     size_t idx;
     size_t gc_alloc_thresh;
     size_t gc_alloc_accum;
@@ -685,6 +685,9 @@ rust_task : public rc_base<rust_task>,
     // Run the gc glue on the task stack.
     void gc(size_t nargs);
 
+    // Disconnect from our supervisor.
+    void unsupervise();
+
     // Notify tasks waiting for us that we are about to die.
     void notify_waiting_tasks();
 
diff --git a/src/rt/rust_task.cpp b/src/rt/rust_task.cpp
index 5e230a589eb..09239c58fd8 100644
--- a/src/rt/rust_task.cpp
+++ b/src/rt/rust_task.cpp
@@ -62,7 +62,7 @@ rust_task::rust_task(rust_dom *dom, rust_task *spawner) :
     state(&dom->running_tasks),
     cond(NULL),
     dptr(0),
-    spawner(spawner),
+    supervisor(spawner),
     idx(0),
     waiting_tasks(dom),
     alarm(this)
@@ -336,12 +336,12 @@ rust_task::fail(size_t nargs) {
     if (this == dom->root_task)
         dom->fail();
     run_after_return(nargs, dom->root_crate->get_unwind_glue());
-    if (spawner) {
+    if (supervisor) {
         dom->log(rust_log::TASK,
                  "task 0x%" PRIxPTR
-                 " propagating failure to parent 0x%" PRIxPTR,
-                 this, spawner);
-        spawner->kill();
+                 " propagating failure to supervisor 0x%" PRIxPTR,
+                 this, supervisor);
+        supervisor->kill();
     }
 }
 
@@ -353,6 +353,15 @@ rust_task::gc(size_t nargs)
     run_after_return(nargs, dom->root_crate->get_gc_glue());
 }
 
+void
+rust_task::unsupervise()
+{
+    dom->log(rust_log::TASK,
+             "task 0x%" PRIxPTR " disconnecting from supervisor 0x%" PRIxPTR,
+             this, supervisor);
+    supervisor = NULL;
+}
+
 void
 rust_task::notify_waiting_tasks()
 {