diff --git a/serde_derive/Cargo.toml b/serde_derive/Cargo.toml
index c308bf75..6966637d 100644
--- a/serde_derive/Cargo.toml
+++ b/serde_derive/Cargo.toml
@@ -25,7 +25,6 @@ proc-macro = true
 [dependencies]
 proc-macro2 = "0.3"
 quote = "0.5.2"
-serde_derive_internals = { version = "=0.23.1", default-features = false, path = "../serde_derive_internals" }
 syn = { version = "0.13", features = ["visit"] }
 
 [dev-dependencies]
diff --git a/serde_derive_internals/src/ast.rs b/serde_derive/src/internals/ast.rs
similarity index 98%
rename from serde_derive_internals/src/ast.rs
rename to serde_derive/src/internals/ast.rs
index 89fac302..9ccb62f5 100644
--- a/serde_derive_internals/src/ast.rs
+++ b/serde_derive/src/internals/ast.rs
@@ -6,11 +6,11 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use attr;
-use check;
+use internals::attr;
+use internals::check;
+use internals::Ctxt;
 use syn;
 use syn::punctuated::Punctuated;
-use Ctxt;
 
 pub struct Container<'a> {
     pub ident: syn::Ident,
diff --git a/serde_derive_internals/src/attr.rs b/serde_derive/src/internals/attr.rs
similarity index 99%
rename from serde_derive_internals/src/attr.rs
rename to serde_derive/src/internals/attr.rs
index 06271a7f..bc60a6e3 100644
--- a/serde_derive_internals/src/attr.rs
+++ b/serde_derive/src/internals/attr.rs
@@ -6,6 +6,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+use internals::Ctxt;
 use proc_macro2::{Group, Span, TokenStream, TokenTree};
 use std::collections::BTreeSet;
 use std::str::FromStr;
@@ -15,7 +16,6 @@ use syn::synom::{ParseError, Synom};
 use syn::Ident;
 use syn::Meta::{List, NameValue, Word};
 use syn::NestedMeta::{Literal, Meta};
-use Ctxt;
 
 // This module handles parsing of `#[serde(...)]` attributes. The entrypoints
 // are `attr::Container::from_ast`, `attr::Variant::from_ast`, and
@@ -25,7 +25,7 @@ use Ctxt;
 // user will see errors simultaneously for all bad attributes in the crate
 // rather than just the first.
 
-pub use case::RenameRule;
+pub use internals::case::RenameRule;
 
 #[derive(Copy, Clone)]
 struct Attr<'c, T> {
@@ -167,6 +167,7 @@ pub enum Identifier {
 }
 
 impl Identifier {
+    #[cfg(feature = "deserialize_in_place")]
     pub fn is_some(self) -> bool {
         match self {
             Identifier::No => false,
diff --git a/serde_derive_internals/src/case.rs b/serde_derive/src/internals/case.rs
similarity index 100%
rename from serde_derive_internals/src/case.rs
rename to serde_derive/src/internals/case.rs
diff --git a/serde_derive_internals/src/check.rs b/serde_derive/src/internals/check.rs
similarity index 98%
rename from serde_derive_internals/src/check.rs
rename to serde_derive/src/internals/check.rs
index 6ca8275b..639f95e9 100644
--- a/serde_derive_internals/src/check.rs
+++ b/serde_derive/src/internals/check.rs
@@ -6,9 +6,9 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use ast::{Container, Data, Style};
-use attr::{EnumTag, Identifier};
-use Ctxt;
+use internals::ast::{Container, Data, Style};
+use internals::attr::{EnumTag, Identifier};
+use internals::Ctxt;
 
 /// Cross-cutting checks that require looking at more than a single attrs
 /// object. Simpler checks should happen when parsing and building the attrs.
diff --git a/serde_derive_internals/src/ctxt.rs b/serde_derive/src/internals/ctxt.rs
similarity index 100%
rename from serde_derive_internals/src/ctxt.rs
rename to serde_derive/src/internals/ctxt.rs
diff --git a/serde_derive/src/internals/mod.rs b/serde_derive/src/internals/mod.rs
new file mode 100644
index 00000000..f68462c9
--- /dev/null
+++ b/serde_derive/src/internals/mod.rs
@@ -0,0 +1,16 @@
+// Copyright 2017 Serde Developers
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+pub mod ast;
+pub mod attr;
+
+mod ctxt;
+pub use self::ctxt::Ctxt;
+
+mod case;
+mod check;
diff --git a/serde_derive/src/lib.rs b/serde_derive/src/lib.rs
index d20ef78d..cd6304ec 100644
--- a/serde_derive/src/lib.rs
+++ b/serde_derive/src/lib.rs
@@ -35,11 +35,11 @@ extern crate quote;
 #[macro_use]
 extern crate syn;
 
-extern crate serde_derive_internals as internals;
-
 extern crate proc_macro;
 extern crate proc_macro2;
 
+mod internals;
+
 use proc_macro::TokenStream;
 use syn::DeriveInput;
 
diff --git a/serde_derive_internals/Cargo.toml b/serde_derive_internals/Cargo.toml
index 45d11906..a782149a 100644
--- a/serde_derive_internals/Cargo.toml
+++ b/serde_derive_internals/Cargo.toml
@@ -9,7 +9,10 @@ repository = "https://github.com/serde-rs/serde"
 documentation = "https://docs.serde.rs/serde_derive_internals/"
 keywords = ["serde", "serialization"]
 readme = "README.md"
-include = ["Cargo.toml", "src/**/*.rs", "README.md", "LICENSE-APACHE", "LICENSE-MIT"]
+include = ["Cargo.toml", "lib.rs", "src/**/*.rs", "README.md", "LICENSE-APACHE", "LICENSE-MIT"]
+
+[lib]
+path = "lib.rs"
 
 [dependencies]
 proc-macro2 = "0.3"
diff --git a/serde_derive_internals/src/lib.rs b/serde_derive_internals/lib.rs
similarity index 88%
rename from serde_derive_internals/src/lib.rs
rename to serde_derive_internals/lib.rs
index 03a48102..cbd307b9 100644
--- a/serde_derive_internals/src/lib.rs
+++ b/serde_derive_internals/lib.rs
@@ -17,11 +17,7 @@ extern crate syn;
 
 extern crate proc_macro2;
 
-pub mod ast;
-pub mod attr;
+#[path = "src/mod.rs"]
+mod internals;
 
-mod ctxt;
-pub use ctxt::Ctxt;
-
-mod case;
-mod check;
+pub use internals::*;
diff --git a/serde_derive_internals/src b/serde_derive_internals/src
new file mode 120000
index 00000000..f1a565f2
--- /dev/null
+++ b/serde_derive_internals/src
@@ -0,0 +1 @@
+../serde_derive/src/internals/
\ No newline at end of file