diff --git a/serde_codegen/Cargo.toml b/serde_codegen/Cargo.toml
index aef24ca9..41f42271 100644
--- a/serde_codegen/Cargo.toml
+++ b/serde_codegen/Cargo.toml
@@ -11,22 +11,14 @@ keywords = ["serde", "serialization"]
 include = ["Cargo.toml", "src/**/*.rs"]
 
 [features]
-default = ["with-syntex"]
 unstable = []
 unstable-testing = ["clippy"]
-with-syntex = [
-    "syntex",
-    "syntex_syntax",
-]
-with-syn = []
 
 [dependencies]
 clippy = { version = "0.*", optional = true }
 quote = "0.3.8"
 serde_codegen_internals = { version = "=0.11.3", default-features = false, path = "../serde_codegen_internals" }
 syn = { version = "0.10", features = ["aster", "visit"] }
-syntex = { version = "0.54", optional = true }
-syntex_syntax = { version = "0.54", optional = true }
 
 [badges]
 travis-ci = { repository = "serde-rs/serde" }
diff --git a/serde_codegen/src/lib.rs b/serde_codegen/src/lib.rs
index 9850fecc..e89cd08c 100644
--- a/serde_codegen/src/lib.rs
+++ b/serde_codegen/src/lib.rs
@@ -8,153 +8,14 @@
 
 extern crate serde_codegen_internals as internals;
 
-#[cfg(feature = "with-syntex")]
-extern crate syntex;
-
-#[cfg(feature = "with-syntex")]
-extern crate syntex_syntax as syntax;
-
 extern crate syn;
 #[macro_use]
 extern crate quote;
 
-#[cfg(feature = "with-syntex")]
-use std::path::Path;
-
 mod bound;
 mod de;
 mod ser;
 
-#[cfg(feature = "with-syntex")]
-fn syntex_registry() -> syntex::Registry {
-    use syntax::{ast, fold};
-
-    /// Strip the serde attributes from the crate.
-    #[cfg(feature = "with-syntex")]
-    fn strip_attributes(krate: ast::Crate) -> ast::Crate {
-        /// Helper folder that strips the serde attributes after the extensions have been expanded.
-        struct StripAttributeFolder;
-
-        impl fold::Folder for StripAttributeFolder {
-            fn fold_attribute(&mut self, attr: ast::Attribute) -> Option<ast::Attribute> {
-                if attr.value.name == "serde" {
-                    if let ast::MetaItemKind::List(..) = attr.value.node {
-                        return None;
-                    }
-                }
-                Some(attr)
-            }
-
-            fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
-                fold::noop_fold_mac(mac, self)
-            }
-        }
-
-        fold::Folder::fold_crate(&mut StripAttributeFolder, krate)
-    }
-
-    let mut reg = syntex::Registry::new();
-
-    reg.add_attr("feature(custom_derive)");
-    reg.add_attr("feature(custom_attribute)");
-
-    reg.add_decorator("derive_Serialize", shim::expand_derive_serialize);
-    reg.add_decorator("derive_Deserialize", shim::expand_derive_deserialize);
-
-    reg.add_post_expansion_pass(strip_attributes);
-
-    reg
-}
-
-#[cfg(feature = "with-syntex")]
-pub fn expand_str(src: &str) -> Result<String, syntex::Error> {
-    let src = src.to_owned();
-
-    let expand_thread = move || {
-        syntex_registry().expand_str("", "", &src)
-    };
-
-    syntex::with_extra_stack(expand_thread)
-}
-
-#[cfg(feature = "with-syntex")]
-pub fn expand<S, D>(src: S, dst: D) -> Result<(), syntex::Error>
-    where S: AsRef<Path>,
-          D: AsRef<Path>,
-{
-    let src = src.as_ref().to_owned();
-    let dst = dst.as_ref().to_owned();
-
-    let expand_thread = move || {
-        syntex_registry().expand("", src, dst)
-    };
-
-    syntex::with_extra_stack(expand_thread)
-}
-
-macro_rules! shim {
-    ($name:ident $pkg:ident :: $func:ident) => {
-        pub fn $func(
-            cx: &mut ::syntax::ext::base::ExtCtxt,
-            span: ::syntax::codemap::Span,
-            meta_item: &::syntax::ast::MetaItem,
-            annotatable: &::syntax::ext::base::Annotatable,
-            push: &mut FnMut(::syntax::ext::base::Annotatable)
-        ) {
-            let item = match *annotatable {
-                ::syntax::ext::base::Annotatable::Item(ref item) => item,
-                _ => {
-                    cx.span_err(
-                        meta_item.span,
-                        concat!("`#[derive(",
-                                stringify!($name),
-                                ")]` may only be applied to structs and enums"));
-                    return;
-                }
-            };
-
-            use syntax::{attr, ast, visit};
-            struct MarkSerdeAttributesUsed;
-            impl<'a> visit::Visitor<'a> for MarkSerdeAttributesUsed {
-                fn visit_attribute(&mut self, attr: &ast::Attribute) {
-                    if attr.value.name == "serde" {
-                        if let ast::MetaItemKind::List(..) = attr.value.node {
-                            attr::mark_used(attr);
-                        }
-                    }
-                }
-            }
-            visit::walk_item(&mut MarkSerdeAttributesUsed, item);
-
-            use syntax::print::pprust;
-            let s = pprust::item_to_string(item);
-
-            use {syn, $pkg};
-            let syn_item = syn::parse_macro_input(&s).unwrap();
-            let expanded = match $pkg::$func(&syn_item) {
-                Ok(expanded) => expanded.to_string(),
-                Err(msg) => {
-                    cx.span_err(span, &msg);
-                    return;
-                }
-            };
-
-            use syntax::parse;
-            let name = stringify!($name).to_string();
-            let sess = cx.parse_sess;
-            let impl_item = parse::parse_item_from_source_str(name, expanded, sess);
-            push(::syntax::ext::base::Annotatable::Item(impl_item.unwrap().unwrap()));
-        }
-    };
-}
-
-#[cfg(feature = "with-syntex")]
-mod shim {
-    shim!(Serialize ser::expand_derive_serialize);
-    shim!(Deserialize de::expand_derive_deserialize);
-}
-
-#[cfg(feature = "with-syn")]
 #[doc(hidden)]
 /// Not public API. Use the serde_derive crate.
 pub fn expand_derive_serialize(item: &str) -> Result<quote::Tokens, String> {
@@ -162,7 +23,6 @@ pub fn expand_derive_serialize(item: &str) -> Result<quote::Tokens, String> {
     ser::expand_derive_serialize(&syn_item)
 }
 
-#[cfg(feature = "with-syn")]
 #[doc(hidden)]
 /// Not public API. Use the serde_derive crate.
 pub fn expand_derive_deserialize(item: &str) -> Result<quote::Tokens, String> {
diff --git a/serde_derive/Cargo.toml b/serde_derive/Cargo.toml
index 311d23c9..75ada3b4 100644
--- a/serde_derive/Cargo.toml
+++ b/serde_derive/Cargo.toml
@@ -17,11 +17,8 @@ travis-ci = { repository = "serde-rs/serde" }
 name = "serde_derive"
 proc-macro = true
 
-[dependencies.serde_codegen]
-version = "=0.9.0"
-path = "../serde_codegen"
-default-features = false
-features = ["with-syn"]
+[dependencies]
+serde_codegen = { version = "=0.9.0", path = "../serde_codegen" }
 
 [dev-dependencies]
 compiletest_rs = "0.2"