diff --git a/.travis.yml b/.travis.yml
index e95df823..bf271d65 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -8,7 +8,7 @@ script:
   - cargo build --verbose
   - cargo test --verbose
   - cargo doc --verbose
-  - ([ $TRAVIS_RUST_VERSION != nightly ] || cargo test --features heap_size)
+  - cargo test --features heapsize
 
 after_success: |
   [ $TRAVIS_RUST_VERSION = nightly ] &&
diff --git a/Cargo.toml b/Cargo.toml
index 46cba33b..616d7d96 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 
 name = "cssparser"
-version = "0.5.6"
+version = "0.5.7"
 authors = [ "Simon Sapin <simon.sapin@exyr.org>" ]
 
 description = "Rust implementation of CSS Syntax Level 3"
@@ -19,11 +19,9 @@ tempdir = "0.3"
 [dependencies]
 encoding = "0.2"
 heapsize = {version = ">=0.1.1, <0.4.0", optional = true}
-heapsize_plugin = {version = "0.1.0", optional = true}
 matches = "0.1"
-serde = {version = ">=0.6.6, <0.8", optional = true}
-serde_macros = {version = ">=0.6.5, <0.8", optional = true}
+serde = {version = ">=0.6.6, <0.9", optional = true}
 
 [features]
-serde-serialization = [ "serde", "serde_macros" ]
-heap_size = [ "heapsize", "heapsize_plugin" ]
+serde-serialization = [ "serde" ]
+heap_size = [ "heapsize" ]
diff --git a/src/color.rs b/src/color.rs
index d64ca77a..12f6fa85 100644
--- a/src/color.rs
+++ b/src/color.rs
@@ -2,16 +2,15 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use std::ascii::AsciiExt;
 use std::fmt;
 
 use super::{Token, Parser, ToCss};
 
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Deserializer, Serialize, Serializer};
 
 /// A color with red, green, blue, and alpha components.
 #[derive(Clone, Copy, PartialEq, Debug)]
-#[cfg_attr(feature = "serde-serialization", derive(Deserialize, Serialize))]
-#[cfg_attr(feature = "heap_size", derive(HeapSizeOf))]
 pub struct RGBA {
     /// The red channel. Nominally in 0.0 ... 1.0.
     pub red: f32,
@@ -23,6 +22,34 @@ pub struct RGBA {
     pub alpha: f32,
 }
 
+#[cfg(feature = "serde")]
+impl Serialize for RGBA {
+    fn serialize<S>(&self, serializer: &mut S) -> Result<(), S::Error>
+        where S: Serializer
+    {
+        (self.red, self.green, self.blue, self.alpha).serialize(serializer)
+    }
+}
+
+#[cfg(feature = "serde")]
+impl Deserialize for RGBA {
+    fn deserialize<D>(deserializer: &mut D) -> Result<Self, D::Error>
+        where D: Deserializer
+    {
+        let (red, green, blue, alpha) =
+            try!(Deserialize::deserialize(deserializer));
+        Ok(RGBA {
+            red: red,
+            green: green,
+            blue: blue,
+            alpha: alpha,
+        })
+    }
+}
+
+#[cfg(feature = "heapsize")]
+known_heap_size!(0, RGBA);
+
 impl ToCss for RGBA {
     fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
         if self.alpha == 1f32 {
@@ -42,7 +69,6 @@ impl ToCss for RGBA {
 
 /// A <color> value.
 #[derive(Clone, Copy, PartialEq, Debug)]
-#[cfg_attr(feature = "heap_size", derive(HeapSizeOf))]
 pub enum Color {
     /// The 'currentColor' keyword
     CurrentColor,
@@ -50,6 +76,9 @@ pub enum Color {
     RGBA(RGBA),
 }
 
+#[cfg(feature = "heapsize")]
+known_heap_size!(0, Color);
+
 impl ToCss for Color {
     fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
         match self {
diff --git a/src/lib.rs b/src/lib.rs
index 85803843..87cc75b9 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -6,12 +6,6 @@
 #![crate_type = "rlib"]
 
 #![deny(missing_docs)]
-#![cfg_attr(feature = "serde-serialization", feature(custom_derive))]
-#![cfg_attr(feature = "serde-serialization", feature(plugin))]
-#![cfg_attr(feature = "serde-serialization", plugin(serde_macros))]
-#![cfg_attr(feature = "heap_size", feature(custom_derive))]
-#![cfg_attr(feature = "heap_size", feature(plugin))]
-#![cfg_attr(feature = "heap_size", plugin(heapsize_plugin))]
 
 /*!
 
@@ -75,8 +69,8 @@ extern crate encoding;
 #[macro_use] extern crate matches;
 #[cfg(test)] extern crate tempdir;
 #[cfg(test)] extern crate rustc_serialize;
-#[cfg(feature = "serde-serialization")] extern crate serde;
-#[cfg(feature = "heap_size")] extern crate heapsize;
+#[cfg(feature = "serde")] extern crate serde;
+#[cfg(feature = "heapsize")] #[macro_use] extern crate heapsize;
 
 pub use tokenizer::{Token, NumericValue, PercentageValue, SourceLocation};
 pub use rules_and_declarations::{parse_important};
diff --git a/src/serializer.rs b/src/serializer.rs
index 69b7255b..ded6bb21 100644
--- a/src/serializer.rs
+++ b/src/serializer.rs
@@ -314,9 +314,11 @@ impl_tocss_for_number!(u64);
 
 /// A category of token. See the `needs_separator_when_before` method.
 #[derive(Copy, Clone, Eq, PartialEq, Debug)]
-#[cfg_attr(feature = "heap_size", derive(HeapSizeOf))]
 pub struct TokenSerializationType(TokenSerializationTypeVariants);
 
+#[cfg(feature = "heapsize")]
+known_heap_size!(0, TokenSerializationType);
+
 impl TokenSerializationType {
     /// Return a value that represents the absence of a token, e.g. before the start of the input.
     pub fn nothing() -> TokenSerializationType {
@@ -363,7 +365,6 @@ impl TokenSerializationType {
 }
 
 #[derive(Copy, Clone, Eq, PartialEq, Debug)]
-#[cfg_attr(feature = "heap_size", derive(HeapSizeOf))]
 enum TokenSerializationTypeVariants {
     Nothing,
     WhiteSpace,