1 files changed, 6 insertions, 5 deletions
diff --git a/src/libgreen/task.rs b/src/libgreen/task.rs
index 183fe8d0555..e1db24e11e4 100644
--- a/src/libgreen/task.rs
+++ b/src/libgreen/task.rs
@@ -450,11 +450,12 @@ impl Runtime for GreenTask {
         }
     }
 
-    fn stack_bounds(&self) -> Option<(uint, uint)> {
-        self.coroutine.as_ref().map(|c| {
-            (c.current_stack_segment.start() as uint,
-             c.current_stack_segment.end() as uint)
-        })
+    fn stack_bounds(&self) -> (uint, uint) {
+        let c = self.coroutine.as_ref()
+            .expect("GreenTask.stack_bounds called without a coroutine");
+
+        (c.current_stack_segment.start() as uint,
+         c.current_stack_segment.end() as uint)
     }
 
     fn wrap(~self) -> ~Any { self as ~Any }