diff --git a/src/libcore/rt/work_queue.rs b/src/libcore/rt/work_queue.rs
index 7011b4ebc104..31f73cd09b54 100644
--- a/src/libcore/rt/work_queue.rs
+++ b/src/libcore/rt/work_queue.rs
@@ -11,39 +11,48 @@
 use container::Container;
 use option::*;
 use vec::OwnedVector;
+use unstable::sync::{Exclusive, exclusive};
+use cell::Cell;
+use kinds::Owned;
 
 pub struct WorkQueue<T> {
-    priv queue: ~[T]
+    // XXX: Another mystery bug fixed by boxing this lock
+    priv queue: ~Exclusive<~[T]>
 }
 
-pub impl<T> WorkQueue<T> {
+pub impl<T: Owned> WorkQueue<T> {
     fn new() -> WorkQueue<T> {
         WorkQueue {
-            queue: ~[]
+            queue: ~exclusive(~[])
         }
     }
 
     fn push(&mut self, value: T) {
-        self.queue.unshift(value)
+        let value = Cell(value);
+        self.queue.with(|q| q.unshift(value.take()) );
     }
 
     fn pop(&mut self) -> Option<T> {
-        if !self.queue.is_empty() {
-            Some(self.queue.shift())
-        } else {
-            None
+        do self.queue.with |q| {
+            if !q.is_empty() {
+                Some(q.shift())
+            } else {
+                None
+            }
         }
     }
 
     fn steal(&mut self) -> Option<T> {
-        if !self.queue.is_empty() {
-            Some(self.queue.pop())
-        } else {
-            None
+        do self.queue.with |q| {
+            if !q.is_empty() {
+                Some(q.pop())
+            } else {
+                None
+            }
         }
     }
 
     fn is_empty(&self) -> bool {
-        return self.queue.is_empty();
+        self.queue.with_imm(|q| q.is_empty() )
     }
 }