diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index de4b642..0a890bf 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -12,3 +12,6 @@ jobs:
     uses: scientist-labs/rust-gem-release/.github/workflows/build.yml@0.11.0
     with:
       test-command: bundle exec rake spec
+      # Match the fat-gem ABI set in release.yml, so PR CI compiles against every
+      # Ruby we ship a binary for - including 4.0.
+      ruby-versions: "3.1,3.2,3.3,3.4,4.0"
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index e7339db..766373e 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -57,6 +57,11 @@ jobs:
       # "spellkit", so ext-name / gemspec / platform-gem-env all resolve to their
       # defaults (spellkit, spellkit.gemspec, RUST_GEM_PLATFORM) and are omitted.
       gem-name: spellkit
+      # 4.0 added in 0.3.0. The shared workflow's default is 3.1-3.4 and deliberately
+      # excludes 4.0, because Ruby 4.0 changed the C API (rb_sys::RTypedData lost
+      # typed_flag, rb_fiber_raise's argv became *mut) and magnus 0.7 cannot compile
+      # against it. spellkit is on magnus 0.8 as of this version, so it can.
+      ruby-versions: "3.1,3.2,3.3,3.4,4.0"
       version-command: ruby -r./lib/spellkit/version -e 'print SpellKit::VERSION'
       version: ${{ inputs.version }}
       bump-command: |
diff --git a/README.md b/README.md
index 29a41a6..ab223ca 100644
--- a/README.md
+++ b/README.md
@@ -684,9 +684,13 @@ bundle exec rake build
 ## Platform Support
 
 Pre-built gems available for:
-- macOS (x86_64, arm64)
-- Linux (glibc, musl)
-- Ruby 3.1, 3.2, 3.3
+- macOS (arm64)
+- Linux (x86_64, aarch64)
+- Ruby 3.1, 3.2, 3.3, 3.4, 4.0
+
+A pre-built gem carries one compiled extension per Ruby ABI, so installing under a Ruby
+outside that list falls back to building from source and needs a Rust toolchain (>= 1.85).
+Ruby 4.0 support arrived in 0.3.0; earlier versions cannot compile against it at all.
 
 ## Contributing
 
diff --git a/ext/spellkit/Cargo.toml b/ext/spellkit/Cargo.toml
index b8030d5..667e713 100644
--- a/ext/spellkit/Cargo.toml
+++ b/ext/spellkit/Cargo.toml
@@ -11,7 +11,7 @@ name = "spellkit"
 crate-type = ["cdylib"]
 
 [dependencies]
-magnus = { version = "0.7", features = ["rb-sys"] }
+magnus = { version = "0.8", features = ["rb-sys"] }
 hashbrown = "0.15"
 unicode-normalization = "0.1"
 regex = "1.11"
diff --git a/ext/spellkit/src/lib.rs b/ext/spellkit/src/lib.rs
index 14b22f6..8b1017c 100644
--- a/ext/spellkit/src/lib.rs
+++ b/ext/spellkit/src/lib.rs
@@ -1,7 +1,7 @@
 mod symspell;
 mod guards;
 
-use magnus::{class, define_module, function, method, prelude::*, Error, RArray, RHash, Ruby, Value, TryConvert};
+use magnus::{function, method, prelude::*, Error, RArray, RHash, Ruby, Value, TryConvert};
 use std::sync::{Arc, RwLock};
 use symspell::SymSpell;
 use guards::Guards;
@@ -264,10 +264,10 @@ impl Checker {
 
         if let Some(ref symspell) = state.symspell {
             let suggestions = symspell.suggestions(&word, max_suggestions);
-            let result = RArray::new();
+            let result = ruby.ary_new();
 
             for suggestion in suggestions {
-                let hash = RHash::new();
+                let hash = ruby.hash_new();
                 hash.aset("term", suggestion.term)?;
                 hash.aset("distance", suggestion.distance)?;
                 hash.aset("freq", suggestion.frequency)?;
@@ -320,7 +320,7 @@ impl Checker {
             return Err(Error::new(ruby.exception_runtime_error(), "Dictionary not loaded. Call load! first"));
         }
 
-        let result = RArray::new();
+        let result = ruby.ary_new();
 
         if let Some(ref symspell) = state.symspell {
             for token in tokens.into_iter() {
@@ -336,8 +336,9 @@ impl Checker {
     }
 
     fn stats(&self) -> Result<RHash, Error> {
+        let ruby = Ruby::get().unwrap();
         let state = self.state.read().unwrap();
-        let stats = RHash::new();
+        let stats = ruby.hash_new();
 
         if !state.loaded {
             stats.aset("loaded", false)?;
@@ -376,9 +377,9 @@ impl Checker {
 }
 
 #[magnus::init]
-fn init(_ruby: &Ruby) -> Result<(), Error> {
-    let module = define_module("SpellKit")?;
-    let checker_class = module.define_class("Checker", class::object())?;
+fn init(ruby: &Ruby) -> Result<(), Error> {
+    let module = ruby.define_module("SpellKit")?;
+    let checker_class = module.define_class("Checker", ruby.class_object())?;
 
     checker_class.define_singleton_method("new", function!(Checker::new, 0))?;
     checker_class.define_method("load!", method!(Checker::load_full, 1))?;
diff --git a/lib/spellkit/version.rb b/lib/spellkit/version.rb
index 23d9915..3ace8a6 100644
--- a/lib/spellkit/version.rb
+++ b/lib/spellkit/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module SpellKit
-  VERSION = "0.2.0"
+  VERSION = "0.3.0"
 end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 844294a..0c3b75a 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -17,4 +17,17 @@
   config.expect_with :rspec do |c|
     c.syntax = :expect
   end
+
+  # `require "webmock/rspec"` in dictionary_loading_spec.rb disables net connect for the
+  # WHOLE suite, not just that file - so the two examples tagged :integration, whose entire
+  # purpose is to prove DEFAULT_DICTIONARY_URL really resolves and loads, were blocked by
+  # WebMock and failed on every Ruby. That is why every build run on this repo has been red.
+  #
+  # Let a tagged example reach the network, and restore the block afterwards so no other
+  # example inherits it.
+  config.around(:each, :integration) do |example|
+    WebMock.allow_net_connect! if defined?(WebMock)
+    example.run
+    WebMock.disable_net_connect!(allow_localhost: true) if defined?(WebMock)
+  end
 end
diff --git a/spellkit.gemspec b/spellkit.gemspec
index 2240e20..afd66bd 100644
--- a/spellkit.gemspec
+++ b/spellkit.gemspec
@@ -56,6 +56,9 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "webmock"
   spec.add_development_dependency "standard", "~> 1.3"
   spec.add_development_dependency "irb"
+  # benchmark left the default gems in Ruby 4.0, so spec/performance_spec.rb's
+  # `require "benchmark"` fails there unless it is declared.
+  spec.add_development_dependency "benchmark"
   spec.add_development_dependency "benchmark-ips"
   spec.add_development_dependency "ffi-aspell"
 end