diff --git a/serde2/serde2_macros/src/lib.rs b/serde2/serde2_macros/src/lib.rs
index 04bf2564..12f00078 100644
--- a/serde2/serde2_macros/src/lib.rs
+++ b/serde2/serde2_macros/src/lib.rs
@@ -1,4 +1,4 @@
-#![feature(plugin_registrar, quote)]
+#![feature(plugin_registrar, quote, unboxed_closures)]
 
 extern crate syntax;
 extern crate rustc;
@@ -62,8 +62,7 @@ fn expand_deriving_serialize<>(cx: &mut ExtCtxt,
                                 sp: Span,
                                 mitem: &MetaItem,
                                 item: &Item,
-                                push: |P<ast::Item>|) //where
-        //F: FnOnce(P<ast::Item>)
+                                mut push: Box<FnMut(P<ast::Item>)>)
 {
     let inline = cx.meta_word(sp, token::InternedString::new("inline"));
     let attrs = vec!(cx.attribute(sp, inline));
@@ -80,12 +79,11 @@ fn expand_deriving_serialize<>(cx: &mut ExtCtxt,
                 generics: LifetimeBounds {
                     lifetimes: Vec::new(),
                     bounds: vec![
-                        ("__S", None, vec![]),
-                        ("__R", None, vec![]),
-                        ("__E", None, vec![]),
+                        ("__S", vec![]),
+                        ("__R", vec![]),
+                        ("__E", vec![]),
                         (
                             "__V",
-                            None,
                             vec![
                                 Path::new_(
                                     vec!["serde2", "ser", "Visitor"],
@@ -130,7 +128,7 @@ fn expand_deriving_serialize<>(cx: &mut ExtCtxt,
         ]
     };
 
-    trait_def.expand(cx, mitem, item, |item| push(item))
+    trait_def.expand(cx, mitem, item, |item| push.call_mut((item,)))
 }
 
 fn serialize_substructure(cx: &ExtCtxt, span: Span, substr: &Substructure) -> P<Expr> {
diff --git a/serde2/src/json/ser.rs b/serde2/src/json/ser.rs
index 57fa3c3e..52895fe3 100644
--- a/serde2/src/json/ser.rs
+++ b/serde2/src/json/ser.rs
@@ -1,7 +1,7 @@
 use std::f64;
 use std::io::{mod, ByRefWriter, IoError};
-use std::num::{Float, FPNaN, FPInfinite};
-use std::str::Utf8Error;
+use std::num::{Float, FpCategory};
+use std::string::FromUtf8Error;
 
 use ser;
 use ser::Serializer;
@@ -225,7 +225,7 @@ pub fn escape_char<W: io::Writer>(wr: &mut W, value: char) -> Result<(), IoError
 
 fn fmt_f64_or_null<W: io::Writer>(wr: &mut W, value: f64) -> Result<(), IoError> {
     match value.classify() {
-        FPNaN | FPInfinite => wr.write_str("null"),
+        FpCategory::Nan | FpCategory::Infinite => wr.write_str("null"),
         _ => wr.write_str(f64::to_str_digits(value, 6).as_slice()),
     }
 }
@@ -252,7 +252,7 @@ pub fn to_vec<
 #[inline]
 pub fn to_string<
     T: ser::Serialize,
->(value: &T) -> Result<Result<String, (Vec<u8>, Utf8Error)>, IoError> {
+>(value: &T) -> Result<Result<String, FromUtf8Error>, IoError> {
     let vec = try!(to_vec(value));
     Ok(String::from_utf8(vec))
 }
diff --git a/serde_macros/src/lib.rs b/serde_macros/src/lib.rs
index 863dc7a4..4aef1ab5 100644
--- a/serde_macros/src/lib.rs
+++ b/serde_macros/src/lib.rs
@@ -1,7 +1,7 @@
 #![crate_name = "serde_macros"]
 #![crate_type = "dylib"]
 
-#![feature(plugin_registrar, quote)]
+#![feature(plugin_registrar, quote, unboxed_closures)]
 
 extern crate syntax;
 extern crate rustc;
@@ -70,7 +70,7 @@ fn expand_deriving_serialize(cx: &mut ExtCtxt,
                              sp: Span,
                              mitem: &MetaItem,
                              item: &Item,
-                             push: |P<ast::Item>|) {
+                             mut push: Box<FnMut(P<ast::Item>)>) {
     let inline = cx.meta_word(sp, token::InternedString::new("inline"));
     let attrs = vec!(cx.attribute(sp, inline));
 
@@ -83,10 +83,10 @@ fn expand_deriving_serialize(cx: &mut ExtCtxt,
         additional_bounds: Vec::new(),
         generics: LifetimeBounds {
             lifetimes: Vec::new(),
-            bounds: vec!(("__S", None, vec!(Path::new_(
+            bounds: vec!(("__S", vec!(Path::new_(
                             vec!("serde", "ser", "Serializer"), None,
                             vec!(box Literal(Path::new_local("__E"))), true))),
-                         ("__E", None, vec!()))
+                         ("__E", vec!()))
         },
         methods: vec!(
             MethodDef {
@@ -113,7 +113,7 @@ fn expand_deriving_serialize(cx: &mut ExtCtxt,
             })
     };
 
-    trait_def.expand(cx, mitem, item, |item| push(item))
+    trait_def.expand(cx, mitem, item, |item| push.call_mut((item,)))
 }
 
 fn serialize_substructure(cx: &ExtCtxt,
@@ -199,7 +199,7 @@ pub fn expand_deriving_deserialize(cx: &mut ExtCtxt,
                                    span: Span,
                                    mitem: &MetaItem,
                                    item: &Item,
-                                   push: |P<Item>|) {
+                                   mut push: Box<FnMut(P<Item>)>) {
     let trait_def = TraitDef {
         span: span,
         attributes: Vec::new(),
@@ -209,10 +209,10 @@ pub fn expand_deriving_deserialize(cx: &mut ExtCtxt,
         additional_bounds: Vec::new(),
         generics: LifetimeBounds {
             lifetimes: Vec::new(),
-            bounds: vec!(("__D", None, vec!(Path::new_(
+            bounds: vec!(("__D", vec!(Path::new_(
                             vec!("serde", "de", "Deserializer"), None,
                             vec!(box Literal(Path::new_local("__E"))), true))),
-                         ("__E", None, vec!()))
+                         ("__E", vec!()))
         },
         methods: vec!(
             MethodDef {
@@ -244,7 +244,7 @@ pub fn expand_deriving_deserialize(cx: &mut ExtCtxt,
             })
     };
 
-    trait_def.expand(cx, mitem, item, |item| push(item))
+    trait_def.expand(cx, mitem, item, |item| push.call_mut((item,)))
 }
 
 fn deserialize_substructure(cx: &mut ExtCtxt,
diff --git a/src/json/ser.rs b/src/json/ser.rs
index ac07b677..2478c813 100644
--- a/src/json/ser.rs
+++ b/src/json/ser.rs
@@ -1,8 +1,8 @@
 use std::f32;
 use std::f64;
-use std::num::{Float, FPNaN, FPInfinite};
+use std::num::{Float, FpCategory};
 use std::io::{IoError, IoResult};
-use std::str::Utf8Error;
+use std::string::FromUtf8Error;
 
 use ser::Serialize;
 use ser;
@@ -52,14 +52,14 @@ fn escape_char<W: Writer>(wr: &mut W, v: char) -> IoResult<()> {
 
 fn fmt_f32_or_null<W: Writer>(wr: &mut W, v: f32) -> IoResult<()> {
     match v.classify() {
-        FPNaN | FPInfinite => wr.write_str("null"),
+        FpCategory::Nan | FpCategory::Infinite => wr.write_str("null"),
         _ => wr.write_str(f32::to_str_digits(v, 6).as_slice()),
     }
 }
 
 fn fmt_f64_or_null<W: Writer>(wr: &mut W, v: f64) -> IoResult<()> {
     match v.classify() {
-        FPNaN | FPInfinite => wr.write_str("null"),
+        FpCategory::Nan | FpCategory::Infinite => wr.write_str("null"),
         _ => wr.write_str(f64::to_str_digits(v, 6).as_slice()),
     }
 }
@@ -600,7 +600,7 @@ pub fn to_vec<
 #[inline]
 pub fn to_string<
     T: Serialize<Serializer<Vec<u8>>, IoError>
->(value: &T) -> Result<String, (Vec<u8>, Utf8Error)> {
+>(value: &T) -> Result<String, FromUtf8Error> {
     let buf = to_vec(value);
     String::from_utf8(buf)
 }
@@ -629,7 +629,7 @@ pub fn to_pretty_vec<
 /// Encode the specified struct into a json `String` buffer.
 pub fn to_pretty_string<
     T: Serialize<PrettySerializer<Vec<u8>>, IoError>
->(value: &T) -> Result<String, (Vec<u8>, Utf8Error)> {
+>(value: &T) -> Result<String, FromUtf8Error> {
     let buf = to_pretty_vec(value);
     String::from_utf8(buf)
 }