diff --git a/src/libsyntax/ext/base.rs b/src/libsyntax/ext/base.rs
index 64ae6162ef4e56060ffd95e56c3a30fec5b607c7..083039995ee955ce5366292ceff367578e6b0a6e 100644
--- a/src/libsyntax/ext/base.rs
+++ b/src/libsyntax/ext/base.rs
@@ -35,18 +35,18 @@ fn expand(&self,
               sp: Span,
               meta_item: &ast::MetaItem,
               item: &ast::Item,
-              push: Box<FnMut(P<ast::Item>)>);
+              push: &mut FnMut(P<ast::Item>));
 }
 
 impl<F> ItemDecorator for F
-    where F : Fn(&mut ExtCtxt, Span, &ast::MetaItem, &ast::Item, Box<FnMut(P<ast::Item>)>)
+    where F : Fn(&mut ExtCtxt, Span, &ast::MetaItem, &ast::Item, &mut FnMut(P<ast::Item>))
 {
     fn expand(&self,
               ecx: &mut ExtCtxt,
               sp: Span,
               meta_item: &ast::MetaItem,
               item: &ast::Item,
-              push: Box<FnMut(P<ast::Item>)>) {
+              push: &mut FnMut(P<ast::Item>)) {
         (*self)(ecx, sp, meta_item, item, push)
     }
 }
diff --git a/src/libsyntax/ext/deriving/mod.rs b/src/libsyntax/ext/deriving/mod.rs
index 9c3fa58ad0960b825d445a1968778741b33fa204..0ed9e85e57677a19f52fbf890d003032e078a41c 100644
--- a/src/libsyntax/ext/deriving/mod.rs
+++ b/src/libsyntax/ext/deriving/mod.rs
@@ -72,7 +72,7 @@ pub fn expand_deprecated_deriving(cx: &mut ExtCtxt,
                                   span: Span,
                                   _: &MetaItem,
                                   _: &Item,
-                                  _: Box<FnMut(P<Item>)>) {
+                                  _: &mut FnMut(P<Item>)) {
     cx.span_err(span, "`deriving` has been renamed to `derive`");
 }
 
@@ -80,7 +80,7 @@ pub fn expand_meta_derive(cx: &mut ExtCtxt,
                           _span: Span,
                           mitem: &MetaItem,
                           item: &Item,
-                          mut push: Box<FnMut(P<Item>)>) {
+                          push: &mut FnMut(P<Item>)) {
     match mitem.node {
         MetaNameValue(_, ref l) => {
             cx.span_err(l.span, "unexpected value in `derive`");
diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index 131bbc4100546985d5436f725fa86c997eef206d..fd98f42c2ab03c0693c21e2f75b74980fdf4f7ec 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -363,7 +363,7 @@ fn expand_mac_invoc<T, F, G>(mac: ast::Mac, span: codemap::Span,
                              mark_thunk: G,
                              fld: &mut MacroExpander)
                              -> Option<T> where
-    F: FnOnce(Box<MacResult>) -> Option<T>,
+    F: for<'a> FnOnce(Box<MacResult+'a>) -> Option<T>,
     G: FnOnce(T, Mrk) -> T,
 {
     match mac.node {
@@ -1102,9 +1102,10 @@ fn expand_annotatable(a: Annotatable,
                     // but that double-mut-borrows fld
                     let mut items: SmallVector<P<ast::Item>> = SmallVector::zero();
                     dec.expand(fld.cx, attr.span, &*attr.node.value, &**it,
-                               box |item| items.push(item));
-                    decorator_items.extend(items.into_iter()
-                        .flat_map(|item| expand_item(item, fld).into_iter()));
+                               &mut |item| items.push(item));
+                    decorator_items.extend(
+                        items.into_iter()
+                             .flat_map(|item| expand_item(item, fld).into_iter()));
 
                     fld.cx.bt_pop();
                 }