diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2b482fa1..f699ee7d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,13 @@
 # Changelog
 
+## 3.4.2 - 2020-10-29
+
+### Changed
+
+- Improve deserialization performance.
+- Publish Windows python3.9 wheel.
+- Disable unsupported SIMD features on non-x86, non-ARM targets
+
 ## 3.4.1 - 2020-10-20
 
 ### Fixed
diff --git a/Cargo.lock b/Cargo.lock
index b9fcb1ea..fc767aa5 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -31,6 +31,12 @@ version = "0.1.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4785bdd1c96b2a846b2bd7cc02e86b6b3dbf14e7e53446c4f54c92a361040822"
 
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
 [[package]]
 name = "cloudabi"
 version = "0.1.0"
@@ -44,7 +50,7 @@ dependencies = [
 name = "encoding_rs"
 version = "0.8.24"
 dependencies = [
- "cfg-if",
+ "cfg-if 0.1.10",
  "packed_simd_2",
 ]
 
@@ -56,11 +62,11 @@ checksum = "cb6ee2a7da03bfc3b66ca47c92c2e392fcc053ea040a85561749b026f7aad09a"
 
 [[package]]
 name = "instant"
-version = "0.1.7"
+version = "0.1.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "63312a18f7ea8760cdd0a7c5aac1a619752a246b833545e3e36d1f81f7cd9e66"
+checksum = "cb1fc4429a33e1f80d41dc9fea4d108a88bec1de8053878898ae448a0b52f613"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
 ]
 
 [[package]]
@@ -77,16 +83,16 @@ checksum = "db65c6da02e61f55dae90a0ae427b2a5f6b3e8db09f58d10efab23af92592616"
 dependencies = [
  "arrayvec",
  "bitflags",
- "cfg-if",
+ "cfg-if 0.1.10",
  "ryu",
  "static_assertions",
 ]
 
 [[package]]
 name = "libc"
-version = "0.2.79"
+version = "0.2.80"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2448f6066e80e3bfc792e9c98bf705b4b0fc6e8ef5b43e5889aff0eaa9c58743"
+checksum = "4d58d1b70b004888f764dfbf6a26a3b0342a1632d33968e4a179d8011c760614"
 
 [[package]]
 name = "libm"
@@ -111,7 +117,7 @@ checksum = "260e51e7efe62b592207e9e13a68e43692a7a279171d6ba57abd208bf23645ad"
 
 [[package]]
 name = "orjson"
-version = "3.4.1"
+version = "3.4.2"
 dependencies = [
  "associative-cache",
  "bytecount",
@@ -133,7 +139,7 @@ version = "0.3.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3278e0492f961fd4ae70909f56b2723a7e8d01a228427294e19cdfdebda89a17"
 dependencies = [
- "cfg-if",
+ "cfg-if 0.1.10",
  "libm",
 ]
 
@@ -154,7 +160,7 @@ version = "0.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c361aa727dd08437f2f1447be8b59a33b0edd15e0fcee698f935613d9efbca9b"
 dependencies = [
- "cfg-if",
+ "cfg-if 0.1.10",
  "cloudabi",
  "instant",
  "libc",
diff --git a/Cargo.toml b/Cargo.toml
index f714f364..f9b74699 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "orjson"
-version = "3.4.1"
+version = "3.4.2"
 authors = ["ijl <ijl@mailbox.org>"]
 description = "Fast, correct Python JSON library supporting dataclasses, datetimes, and numpy"
 edition = "2018"
diff --git a/README.md b/README.md
index 4b2397fe..c75db7c7 100644
--- a/README.md
+++ b/README.md
@@ -1147,13 +1147,13 @@ This is an example of building a wheel using the repository as source,
 
 ```sh
 pip install maturin
-curl https://sh.rustup.rs -sSf | sh -s -- --default-toolchain nightly-2020-10-19 --profile minimal -y
+curl https://sh.rustup.rs -sSf | sh -s -- --default-toolchain nightly-2020-10-24 --profile minimal -y
 maturin build --no-sdist --release --strip --manylinux off
 ls -1 target/wheels
 ```
 
 Problems with the Rust nightly channel may require pinning a version.
-`nightly-2020-10-19` is known to be ok.
+`nightly-2020-10-24` is known to be ok.
 
 orjson is tested for amd64 and aarch64 on Linux, macOS, and Windows. It
 may not work on 32-bit targets. It should be compiled with
diff --git a/pyproject.toml b/pyproject.toml
index 3dd811b4..008ceec5 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ repository = "https://github.com/ijl/orjson"
 
 [build-system]
 build-backend = "maturin"
-requires = ["maturin>=0.8.1,<0.9"]
+requires = ["maturin>=0.8.1,<0.10"]
 
 [tool.maturin]
 manylinux = "off"