diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 6e92b044b..2a7801990 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -353,7 +353,7 @@ jobs:
       - name: Set up Ruby
         uses: ruby/setup-ruby@e81a8fa391b11a595c1b7ed84177cc0fe02faf83 # v1.328.0
         with:
-          ruby-version: '3.3'
+          ruby-version: '3.4'
 
       - name: Compile the skill-eval patterns
         run: make check-eval-patterns
@@ -494,7 +494,7 @@ jobs:
       - name: Set up Ruby
         uses: ruby/setup-ruby@e81a8fa391b11a595c1b7ed84177cc0fe02faf83 # v1.328.0
         with:
-          ruby-version: '3.3'
+          ruby-version: '3.4'
 
       - name: Run skill evals
         env:
diff --git a/.mise.toml b/.mise.toml
index e27c26e44..36cfa4aa6 100644
--- a/.mise.toml
+++ b/.mise.toml
@@ -17,4 +17,4 @@ zizmor = "1.30.0"
 # .github/workflows/test.yml. make check compiles the skill-eval patterns under
 # Ruby's own regex engine, so bin/ci needs the same Ruby CI uses — a different
 # engine would answer a different question.
-ruby = "3.3"
+ruby = "3.4"
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 7b29bb7e4..91db450ad 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -41,7 +41,7 @@ The `go.work` file is gitignored - your local setup won't affect the repo.
 - [bats-core](https://github.com/bats-core/bats-core) for integration tests
 - [golangci-lint](https://golangci-lint.run/) for linting
 - [jq](https://jqlang.github.io/jq/) for CLI surface checks
-- Ruby 3.3 for the skill-eval pattern check, which compiles those patterns
+- Ruby 3.4 for the skill-eval pattern check, which compiles those patterns
   under the same engine the eval runner uses
 
 ## Pull Request Process
diff --git a/flake.lock b/flake.lock
index a682097d9..fba2492bf 100644
--- a/flake.lock
+++ b/flake.lock
@@ -2,11 +2,11 @@
   "nodes": {
     "nixpkgs": {
       "locked": {
-        "lastModified": 1787814960,
-        "narHash": "sha256-PYZq1qzCJXC2zGI0mH07vrZBsw6DRBAOX0jN1pPtqOQ=",
+        "lastModified": 1792506237,
+        "narHash": "sha256-Q/8KLB6jNfpaUN1HAedE/u/Et9feE/zYSsutBLKrCFk=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "c27cdad491a991b11ed731760aa2ef8db0cb0410",
+        "rev": "5adc50831c259f87faeb09ddf930d43597197473",
         "type": "github"
       },
       "original": {
diff --git a/flake.nix b/flake.nix
index 685a583c5..bbe2b620e 100644
--- a/flake.nix
+++ b/flake.nix
@@ -41,7 +41,7 @@
               # Keep in sync with .mise.toml and the ruby/setup-ruby pins in
               # .github/workflows/test.yml: make check compiles the skill-eval
               # patterns under Ruby's own regex engine.
-              ruby_3_3
+              ruby_3_4
               zizmor
             ];
           };