diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a56990e..5a641ea 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -26,8 +26,8 @@ jobs:
     - name: Install uv
       uses: astral-sh/setup-uv@681c641aba71e4a1c380be3ab5e12ad51f415867
 
-    - name: Install dependencies
-      run: uv sync --all-extras
+    - name: Install dependencies (fails if uv.lock is out of sync)
+      run: uv sync --locked --all-extras
 
     - name: Run linter
       run: make lint