diff --git a/CHANGELOG.md b/CHANGELOG.md
index f5424251a388cb49a31beb4c6264bd69128e2c29_Q0hBTkdFTE9HLm1k..45eefc3a1551cda0884efa36f4562b9091a7db07_Q0hBTkdFTE9HLm1k 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 f5424251a388cb49a31beb4c6264bd69128e2c29_Q2FyZ28ubG9jaw==..45eefc3a1551cda0884efa36f4562b9091a7db07_Q2FyZ28ubG9jaw== 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -32,6 +32,12 @@
 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"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -44,7 +50,7 @@
 name = "encoding_rs"
 version = "0.8.24"
 dependencies = [
- "cfg-if",
+ "cfg-if 0.1.10",
  "packed_simd_2",
 ]
 
@@ -56,5 +62,5 @@
 
 [[package]]
 name = "instant"
-version = "0.1.7"
+version = "0.1.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -60,3 +66,3 @@
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "63312a18f7ea8760cdd0a7c5aac1a619752a246b833545e3e36d1f81f7cd9e66"
+checksum = "cb1fc4429a33e1f80d41dc9fea4d108a88bec1de8053878898ae448a0b52f613"
 dependencies = [
@@ -62,5 +68,5 @@
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
 ]
 
 [[package]]
@@ -77,10 +83,10 @@
 dependencies = [
  "arrayvec",
  "bitflags",
- "cfg-if",
+ "cfg-if 0.1.10",
  "ryu",
  "static_assertions",
 ]
 
 [[package]]
 name = "libc"
@@ -81,8 +87,8 @@
  "ryu",
  "static_assertions",
 ]
 
 [[package]]
 name = "libc"
-version = "0.2.79"
+version = "0.2.80"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -88,5 +94,5 @@
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2448f6066e80e3bfc792e9c98bf705b4b0fc6e8ef5b43e5889aff0eaa9c58743"
+checksum = "4d58d1b70b004888f764dfbf6a26a3b0342a1632d33968e4a179d8011c760614"
 
 [[package]]
 name = "libm"
@@ -111,7 +117,7 @@
 
 [[package]]
 name = "orjson"
-version = "3.4.1"
+version = "3.4.2"
 dependencies = [
  "associative-cache",
  "bytecount",
@@ -133,7 +139,7 @@
 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 @@
 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 f5424251a388cb49a31beb4c6264bd69128e2c29_Q2FyZ28udG9tbA==..45eefc3a1551cda0884efa36f4562b9091a7db07_Q2FyZ28udG9tbA== 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 f5424251a388cb49a31beb4c6264bd69128e2c29_UkVBRE1FLm1k..45eefc3a1551cda0884efa36f4562b9091a7db07_UkVBRE1FLm1k 100644
--- a/README.md
+++ b/README.md
@@ -1147,9 +1147,9 @@
 
 ```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.
@@ -1151,9 +1151,9 @@
 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 f5424251a388cb49a31beb4c6264bd69128e2c29_cHlwcm9qZWN0LnRvbWw=..45eefc3a1551cda0884efa36f4562b9091a7db07_cHlwcm9qZWN0LnRvbWw= 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@
 
 [build-system]
 build-backend = "maturin"
-requires = ["maturin>=0.8.1,<0.9"]
+requires = ["maturin>=0.8.1,<0.10"]
 
 [tool.maturin]
 manylinux = "off"