diff --git a/ci/php.yml b/ci/php.yml
index 5053b43..f811a18 100644
--- a/ci/php.yml
+++ b/ci/php.yml
@@ -15,7 +15,7 @@ jobs:
     - uses: actions/checkout@v2
 
     - name: Validate composer.json and composer.lock
-      run: composer validate
+      run: composer validate --strict
 
     - name: Cache Composer packages
       id: composer-cache