diff --git a/.travis.yml b/.travis.yml
index 682b7737..bd1a2cb6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -11,7 +11,7 @@ matrix:
       env: TARGET=x86_64-apple-darwin
       cache: cargo
     - os: linux
-      rust: 1.24.0
+      rust: 1.27.0
       env: TARGET=x86_64-unknown-linux-gnu
       cache: cargo
     - os: linux
diff --git a/Cargo.toml b/Cargo.toml
index f9d08543..1107725f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -48,7 +48,6 @@ optional = true
 version = "1.0.1"
 
 [dependencies.cloudflare-zlib-sys]
-optional = true
 version = "^0.1.2"
 
 [dependencies.image]
@@ -63,11 +62,10 @@ binary = [
 ]
 default = ["binary", "parallel"]
 parallel = ["rayon"]
-cfzlib = ["cloudflare-zlib-sys"]
 dev = [
     "nightly-binary",
 ]
-nightly = ["cfzlib"]
+nightly = []
 nightly-binary = [
     "binary",
     "nightly",
diff --git a/README.md b/README.md
index 58f38949..0d9d3755 100644
--- a/README.md
+++ b/README.md
@@ -26,7 +26,7 @@ cargo build --release
 cp target/release/oxipng /usr/local/bin
 ```
 
-The current minimum supported Rust version is **1.24.0**. Oxipng may compile on earlier versions of Rust,
+The current minimum supported Rust version is **1.27.0**. Oxipng may compile on earlier versions of Rust,
 but there is no guarantee.
 
 Oxipng follows Semantic Versioning.
diff --git a/README.template.md b/README.template.md
index 9f5e020e..f7f3a1f4 100644
--- a/README.template.md
+++ b/README.template.md
@@ -26,7 +26,7 @@ cargo build --release
 cp target/release/oxipng /usr/local/bin
 ```
 
-The current minimum supported Rust version is **1.24.0**. Oxipng may compile on earlier versions of Rust,
+The current minimum supported Rust version is **1.27.0**. Oxipng may compile on earlier versions of Rust,
 but there is no guarantee.
 
 Oxipng follows Semantic Versioning.
diff --git a/src/deflate/mod.rs b/src/deflate/mod.rs
index b8541555..01f31b7a 100644
--- a/src/deflate/mod.rs
+++ b/src/deflate/mod.rs
@@ -15,17 +15,13 @@ pub fn inflate(data: &[u8]) -> Result<Vec<u8>, PngError> {
 
 /// Compress a data stream using the DEFLATE algorithm
 pub fn deflate(data: &[u8], zc: u8, zs: u8, zw: u8, max_size: &AtomicMin) -> Result<Vec<u8>, PngError> {
-    #[cfg(feature = "cfzlib")]
-    {
-        if is_cfzlib_supported() {
-            return cfzlib_deflate(data, zc, zs, zw, max_size)
-        }
+    if is_cfzlib_supported() {
+        return cfzlib_deflate(data, zc, zs, zw, max_size)
     }
 
     miniz_stream::compress_to_vec_oxipng(data, zc, zw.into(), zs.into(), max_size)
 }
 
-#[cfg(feature = "cfzlib")]
 fn is_cfzlib_supported() -> bool {
     #[cfg(target_arch = "x86_64")] {
         if is_x86_feature_detected!("sse4.2") && is_x86_feature_detected!("pclmulqdq") {
@@ -40,7 +36,6 @@ fn is_cfzlib_supported() -> bool {
     false
 }
 
-#[cfg(feature = "cfzlib")]
 pub fn cfzlib_deflate(data: &[u8], level: u8, strategy: u8, window_bits: u8, max_size: &AtomicMin) -> Result<Vec<u8>, PngError> {
     use std::mem;
     use cloudflare_zlib_sys::*;
diff --git a/src/lib.rs b/src/lib.rs
index 1edff34b..d8063e50 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -8,7 +8,6 @@ extern crate num_cpus;
 #[cfg(feature = "parallel")]
 extern crate rayon;
 extern crate zopfli;
-#[cfg(feature = "cfzlib")]
 extern crate cloudflare_zlib_sys;
 
 use image::{DynamicImage, GenericImage, ImageFormat, Pixel};
diff --git a/src/main.rs b/src/main.rs
index 01c43dd0..deb05d29 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -275,7 +275,6 @@ fn collect_files(files: Vec<PathBuf>, out_dir: &Option<PathBuf>, out_file: &OutF
     in_out_pairs
 }
 
-#[cfg_attr(feature = "clippy", allow(cyclomatic_complexity))]
 fn parse_opts_into_struct(matches: &ArgMatches) -> Result<(OutFile, Option<PathBuf>, Options), String> {
     let mut opts = if let Some(x) = matches.value_of("optimization") {
         if let Ok(opt) = x.parse::<u8>() {