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.toml b/Cargo.toml
index 69c86ef5..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" }
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.