diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index d8de42a6..bd2bd068 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -30,7 +30,7 @@ jobs:
       - name: Test
         run: |
           rustup component add clippy
-          cargo install cargo-machete
+          cargo install cargo-machete -f
           cargo machete
           cargo clippy
           cargo test
diff --git a/.github/workflows/release-crate.yml b/.github/workflows/release-crate.yml
new file mode 100644
index 00000000..ba5c2221
--- /dev/null
+++ b/.github/workflows/release-crate.yml
@@ -0,0 +1,15 @@
+name: "Release Crate"
+on:
+  workflow_dispatch:
+jobs:
+  publish_crate:
+    name: Publish Crate
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions-rs/cargo@v1
+        if: startsWith(github.ref, 'refs/tags/v')
+        name: Release Crate
+        with:
+          command: publish
+          args: --manifest-path autocorrect/Cargo.toml --token ${{ secrets.CARGO_REGISTRY_TOKEN }}
diff --git a/.github/workflows/release-crate-gem.yml b/.github/workflows/release-rubygem.yml
similarity index 72%
rename from .github/workflows/release-crate-gem.yml
rename to .github/workflows/release-rubygem.yml
index f25d6ac5..98c5fee0 100644
--- a/.github/workflows/release-crate-gem.yml
+++ b/.github/workflows/release-rubygem.yml
@@ -1,22 +1,11 @@
-name: "Release Crate & RubyGem"
+name: "Release RubyGem"
 on:
   workflow_dispatch:
+  push:
+    branches:
+      - support-ruby-4.0
 jobs:
-  publish_crate:
-    name: Publish Crate
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-      - uses: actions-rs/cargo@v1
-        if: startsWith(github.ref, 'refs/tags/v')
-        name: Release Crate
-        with:
-          command: publish
-          args: --manifest-path autocorrect/Cargo.toml --token ${{ secrets.CARGO_REGISTRY_TOKEN }}
-
   build:
-    needs:
-      - publish_crate
     name: Build compile gems
     runs-on: ubuntu-latest
     strategy:
@@ -30,9 +19,9 @@ jobs:
           - x86_64-linux-musl
     steps:
       - uses: actions/checkout@v4
-      - uses: oxidize-rb/actions/setup-ruby-and-rust@v1.3.0
+      - uses: oxidize-rb/actions/setup-ruby-and-rust@v1.4.4
         with:
-          ruby-version: "3.4"
+          ruby-version: "4.0"
           bundler-cache: true
           cargo-cache: true
           cargo-vendor: false
@@ -41,11 +30,11 @@ jobs:
         run: |
           touch Rakefile
 
-      - uses: oxidize-rb/actions/cross-gem@v1.3.0
+      - uses: oxidize-rb/actions/cross-gem@v1.4.4
         with:
           platform: ${{ matrix.ruby-platform }}
           working-directory: autocorrect-rb/
-          ruby-versions: "3.4, 3.3, 3.2" # optional
+          ruby-versions: "4.0, 3.4, 3.3"
 
       - name: Upload Gem
         uses: actions/upload-artifact@v4
@@ -55,14 +44,12 @@ jobs:
 
   build_source:
     name: Build source gem
-    needs:
-      - publish_crate
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: oxidize-rb/actions/setup-ruby-and-rust@v1.3.0
+      - uses: oxidize-rb/actions/setup-ruby-and-rust@v1.4.4
         with:
-          ruby-version: "3.4"
+          ruby-version: "4.0"
           bundler-cache: false
           cargo-cache: true
           cargo-vendor: true
@@ -89,7 +76,7 @@ jobs:
     steps:
       - uses: ruby/setup-ruby@v1
         with:
-          ruby-version: "3.4"
+          ruby-version: "4.0"
           bundler-cache: true
       - uses: actions/download-artifact@v4
         with:
@@ -97,8 +84,9 @@ jobs:
 
       - name: Display structure of built gems
         run: |
-          mv -f **/autocorrect-*.gem ./
-          ls -lha autocorrect-*.gem
+          mkdir -p dist/
+          cp -n cross-gem-*/*.gem dist/
+          tree
         working-directory: pkg/
 
       - name: Publish to RubyGem
@@ -110,7 +98,7 @@ jobs:
           touch $HOME/.gem/credentials
           chmod 0600 $HOME/.gem/credentials
           printf -- "---\n:rubygems_api_key: ${RUBYGEM_TOKEN}\n" > $HOME/.gem/credentials
-          for filename in autocorrect-*.gem; do
+          for filename in dist/autocorrect-*.gem; do
             echo $filename
             gem push $filename
           done
diff --git a/Cargo.lock b/Cargo.lock
index f90f8602..d8faea9c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -493,7 +493,7 @@ dependencies = [
  "bitflags 2.9.1",
  "cexpr",
  "clang-sys",
- "itertools 0.12.1",
+ "itertools 0.10.5",
  "lazy_static",
  "lazycell",
  "proc-macro2",
@@ -1937,15 +1937,6 @@ dependencies = [
  "either",
 ]
 
-[[package]]
-name = "itertools"
-version = "0.12.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ba291022dbbd398a455acf126c1e341954079855bc60dfdda641363bd6922569"
-dependencies = [
- "either",
-]
-
 [[package]]
 name = "itertools"
 version = "0.14.0"
@@ -2046,7 +2037,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "07033963ba89ebaf1584d767badaa2e8fcec21aedea6b8c0346d487d49c28667"
 dependencies = [
  "cfg-if",
- "windows-targets 0.53.2",
+ "windows-targets 0.48.5",
 ]
 
 [[package]]
@@ -2121,9 +2112,8 @@ dependencies = [
 
 [[package]]
 name = "magnus"
-version = "0.7.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3d87ae53030f3a22e83879e666cb94e58a7bdf31706878a0ba48752994146dab"
+version = "0.9.0"
+source = "git+https://github.com/matsadler/magnus.git?rev=c7e33c181c44860a33e7d8cd8f39090145f061d0#c7e33c181c44860a33e7d8cd8f39090145f061d0"
 dependencies = [
  "magnus-macros",
  "rb-sys",
@@ -2133,9 +2123,8 @@ dependencies = [
 
 [[package]]
 name = "magnus-macros"
-version = "0.6.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5968c820e2960565f647819f5928a42d6e874551cab9d88d75e3e0660d7f71e3"
+version = "0.9.0"
+source = "git+https://github.com/matsadler/magnus.git?rev=c7e33c181c44860a33e7d8cd8f39090145f061d0#c7e33c181c44860a33e7d8cd8f39090145f061d0"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -2883,18 +2872,18 @@ dependencies = [
 
 [[package]]
 name = "rb-sys"
-version = "0.9.116"
+version = "0.9.124"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7059846f68396df83155779c75336ca24567741cb95256e6308c9fcc370e8dad"
+checksum = "c85c4188462601e2aa1469def389c17228566f82ea72f137ed096f21591bc489"
 dependencies = [
  "rb-sys-build",
 ]
 
 [[package]]
 name = "rb-sys-build"
-version = "0.9.116"
+version = "0.9.124"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ac217510df41b9ffc041573e68d7a02aaff770c49943c7494441c4b224b0ecd0"
+checksum = "568068db4102230882e6d4ae8de6632e224ca75fe5970f6e026a04e91ed635d3"
 dependencies = [
  "bindgen",
  "lazy_static",
@@ -2907,9 +2896,9 @@ dependencies = [
 
 [[package]]
 name = "rb-sys-env"
-version = "0.1.2"
+version = "0.2.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a35802679f07360454b418a5d1735c89716bde01d35b1560fc953c1415a0b3bb"
+checksum = "cca7ad6a7e21e72151d56fe2495a259b5670e204c3adac41ee7ef676ea08117a"
 
 [[package]]
 name = "redox_syscall"
diff --git a/Makefile b/Makefile
index 71546f87..75954dc9 100644
--- a/Makefile
+++ b/Makefile
@@ -37,7 +37,7 @@ test\:node\:cli:
 test\:python:
 	cd autocorrect-py && python3 -m pip install . &&  python3 -m pytest
 test\:ruby:
-	cd autocorrect-rb && bundle && rake compile && rake test
+	cd autocorrect-rb && bundle && bundle exec rake compile && bundle exec rake test
 test\:java:
 	cd autocorrect-java && make test
 install:
diff --git a/autocorrect-rb/Gemfile.lock b/autocorrect-rb/Gemfile.lock
index df1bab23..1a73d29d 100644
--- a/autocorrect-rb/Gemfile.lock
+++ b/autocorrect-rb/Gemfile.lock
@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    autocorrect-rb (2.13.0)
+    autocorrect-rb (2.16.3)
       rb_sys (>= 0.9.105)
 
 GEM
@@ -31,7 +31,9 @@ GEM
       concurrent-ruby (~> 1.0)
     logger (1.6.4)
     memory_profiler (1.1.0)
-    minitest (5.25.4)
+    minitest (6.0.1)
+      prism (~> 1.5)
+    prism (1.9.0)
     rake (13.2.1)
     rake-compiler (1.2.8)
       rake
@@ -47,6 +49,7 @@ PLATFORMS
   arm64-darwin-22
   arm64-darwin-23
   arm64-darwin-24
+  arm64-darwin-25
   x86_64-linux
 
 DEPENDENCIES
diff --git a/autocorrect-rb/ext/autocorrect/Cargo.toml b/autocorrect-rb/ext/autocorrect/Cargo.toml
index 9657ceee..0f7795a5 100644
--- a/autocorrect-rb/ext/autocorrect/Cargo.toml
+++ b/autocorrect-rb/ext/autocorrect/Cargo.toml
@@ -10,4 +10,5 @@ name = "autocorrect"
 
 [dependencies]
 autocorrect = "2"
-magnus = "0.7"
+# Wait 0.9.0
+magnus = { git = "https://github.com/matsadler/magnus.git", rev = "c7e33c181c44860a33e7d8cd8f39090145f061d0" }
diff --git a/autocorrect-rb/ext/autocorrect/src/lib.rs b/autocorrect-rb/ext/autocorrect/src/lib.rs
index fc78a839..4c1d41c7 100644
--- a/autocorrect-rb/ext/autocorrect/src/lib.rs
+++ b/autocorrect-rb/ext/autocorrect/src/lib.rs
@@ -1,4 +1,4 @@
-use magnus::{define_class, function, method, Error, IntoValue, Module, Object};
+use magnus::{Error, IntoValue, Module, Object, Ruby, function, method};
 
 #[derive(Debug, Clone)]
 pub struct LineResult {
@@ -137,14 +137,14 @@ pub fn load_config(config_str: String) {
 }
 
 #[magnus::init(name = "autocorrect")]
-fn init() -> Result<(), Error> {
-    let class = define_class("AutoCorrect", magnus::class::object())?;
+fn init(ruby: &Ruby) -> Result<(), Error> {
+    let class = ruby.define_class("AutoCorrect", ruby.class_object())?;
     class.define_singleton_method("format", function!(format, 1))?;
     class.define_singleton_method("format_for", function!(format_for, 2))?;
     class.define_singleton_method("lint_for", function!(lint_for, 2))?;
     class.define_singleton_method("load_config", function!(load_config, 1))?;
 
-    let ignorer_class = class.define_class("Ignorer", magnus::class::object())?;
+    let ignorer_class = class.define_class("Ignorer", ruby.class_object())?;
     ignorer_class.define_singleton_method("new", function!(Ignorer::new, 1))?;
     ignorer_class.define_method("ignored?", method!(Ignorer::is_ignored, 1))?;