diff --git a/src/librustrt/args.rs b/src/librustrt/args.rs
index d94f731e75c6..4632eca4d0fd 100644
--- a/src/librustrt/args.rs
+++ b/src/librustrt/args.rs
@@ -128,7 +128,7 @@ mod imp {
             assert!(take() == Some(expected.clone()));
             assert!(take() == None);
 
-            (|| {
+            (|&mut:| {
             }).finally(|| {
                 // Restore the actual global state.
                 match saved_value {