diff --git a/.github/workflows/oxipng.yml b/.github/workflows/oxipng.yml
index c305fbad..a9e634df 100644
--- a/.github/workflows/oxipng.yml
+++ b/.github/workflows/oxipng.yml
@@ -171,7 +171,7 @@ jobs:
         uses: Swatinem/rust-cache@v2
 
       - name: Install MSRV Rust toolchain
-        uses: dtolnay/rust-toolchain@1.65.0
+        uses: dtolnay/rust-toolchain@1.66.0
 
       - name: Install nextest
         uses: taiki-e/install-action@nextest
diff --git a/Cargo.lock b/Cargo.lock
index 422f295d..5466053c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -385,9 +385,9 @@ checksum = "ef53942eb7bf7ff43a617b3e2c1c4a5ecf5944a7c1bc12d7ee39bbb15e5c1519"
 
 [[package]]
 name = "log"
-version = "0.4.19"
+version = "0.4.20"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b06a4cde4c0f271a446782e3eff8de789548ce57dbc8eca9292c27f4a42004b4"
+checksum = "b5e6163cb8c49088c2c36f57875e58ccd8c87c7427f7fbd50ea6710b2f3f2e8f"
 
 [[package]]
 name = "memoffset"
@@ -571,9 +571,9 @@ checksum = "bebd363326d05ec3e2f532ab7660680f3b02130d780c299bca73469d521bc0ed"
 
 [[package]]
 name = "simd-adler32"
-version = "0.3.5"
+version = "0.3.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "238abfbb77c1915110ad968465608b68e869e0772622c9656714e73e5a1a522f"
+checksum = "d66dc143e6b11c1eddc06d5c423cfc97062865baf299914ab64caa38182078fe"
 
 [[package]]
 name = "strsim"
@@ -716,9 +716,9 @@ dependencies = [
 
 [[package]]
 name = "zopfli"
-version = "0.7.4"
+version = "0.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4e0650ae6a051326d798eb099b632f1afb0d323d25ee4ec82ffb0779512084d5"
+checksum = "5c1f48f3508a3a3f2faee01629564400bc12260f6214a056d06a3aaaa6ef0736"
 dependencies = [
  "crc32fast",
  "log",
diff --git a/Cargo.toml b/Cargo.toml
index 77e8dd79..0120f831 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -10,7 +10,7 @@ license = "MIT"
 name = "oxipng"
 repository = "https://github.com/shssoichiro/oxipng"
 version = "8.0.0"
-rust-version = "1.65.0"
+rust-version = "1.66.0"
 
 [badges]
 travis-ci = { repository = "shssoichiro/oxipng", branch = "master" }
@@ -27,7 +27,7 @@ name = "zopfli"
 required-features = ["zopfli"]
 
 [dependencies]
-zopfli = { version = "0.7.4", optional = true, default-features = false, features = ["std", "zlib"] }
+zopfli = { version = "0.8.0", optional = true, default-features = false, features = ["std", "zlib"] }
 rgb = "0.8.36"
 indexmap = "2.0.0"
 libdeflater = "1.19.0"
diff --git a/README.md b/README.md
index 04189a9c..ddaf1e88 100644
--- a/README.md
+++ b/README.md
@@ -32,7 +32,7 @@ cargo build --release
 cp target/release/oxipng /usr/local/bin
 ```
 
-The current minimum supported Rust version is **1.65.0**.
+The current minimum supported Rust version is **1.66.0**.
 
 Oxipng follows Semantic Versioning.
 
diff --git a/README.template.md b/README.template.md
index 6f14ed8d..6abf1d58 100644
--- a/README.template.md
+++ b/README.template.md
@@ -32,7 +32,7 @@ cargo build --release
 cp target/release/oxipng /usr/local/bin
 ```
 
-The current minimum supported Rust version is **1.65.0**.
+The current minimum supported Rust version is **1.66.0**.
 
 Oxipng follows Semantic Versioning.
 
diff --git a/src/deflate/zopfli_oxipng.rs b/src/deflate/zopfli_oxipng.rs
index b59b93df..651632a9 100644
--- a/src/deflate/zopfli_oxipng.rs
+++ b/src/deflate/zopfli_oxipng.rs
@@ -2,14 +2,12 @@ use crate::{PngError, PngResult};
 use std::num::NonZeroU8;
 
 pub fn deflate(data: &[u8], iterations: NonZeroU8) -> PngResult<Vec<u8>> {
-    use std::cmp::max;
-
-    let mut output = Vec::with_capacity(max(1024, data.len() / 20));
+    let mut output = Vec::with_capacity(data.len());
     let options = zopfli::Options {
-        iteration_count: iterations,
+        iteration_count: iterations.into(),
         ..Default::default()
     };
-    match zopfli::compress(&options, &zopfli::Format::Zlib, data, &mut output) {
+    match zopfli::compress(options, zopfli::Format::Zlib, data, &mut output) {
         Ok(_) => (),
         Err(_) => return Err(PngError::new("Failed to compress in zopfli")),
     };