diff --git a/CHANGELOG.md b/CHANGELOG.md
index ce097794..768f9bcd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,7 @@
-**Version 0.12.1 [unreleased]**
+**Version 0.13.0**
  - Fix bug in certain PNG headers when reducing color type ([#52](https://github.com/shssoichiro/oxipng/issues/52))
+ - [SEMVER_MAJOR] Reduction functions now take `&mut PngData` and return a `bool` indicating whether the image was reduced
+ - Bump minimum required rust version to 1.11.0
 
 **Version 0.12.0**
  - Performance optimizations
diff --git a/Cargo.lock b/Cargo.lock
index d0c8d3db..3ddf81a3 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1,6 +1,6 @@
 [root]
 name = "oxipng"
-version = "0.12.0"
+version = "0.13.0"
 dependencies = [
  "bit-vec 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "byteorder 0.5.3 (registry+https://github.com/rust-lang/crates.io-index)",
diff --git a/Cargo.toml b/Cargo.toml
index f0404684..cbed5400 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -7,7 +7,7 @@ homepage = "https://github.com/shssoichiro/oxipng"
 license = "MIT"
 name = "oxipng"
 repository = "https://github.com/shssoichiro/oxipng"
-version = "0.12.0"
+version = "0.13.0"
 
 [lib]
 name = "oxipng"
diff --git a/src/deflate/mod.rs b/src/deflate/mod.rs
index 4eee5386..ce92f5fc 100644
--- a/src/deflate/mod.rs
+++ b/src/deflate/mod.rs
@@ -5,7 +5,9 @@ use libc::c_int;
 use std::cmp::max;
 use zopfli;
 
+#[doc(hidden)]
 pub mod libz_stream;
+#[doc(hidden)]
 pub mod miniz_stream;
 
 /// Decompress a data stream using the DEFLATE algorithm