diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index d2b7e2c4..159d8343 100755
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -9,8 +9,17 @@ variables:
   DOCKER_DRIVER: overlay2
 
 stages:
+  - test
   - deploy
 
+
+lint_python_on_merge_request:
+    image: python:alpine
+    stage: test
+    script:
+     - echo "Linting Python code"
+     - pip install --upgrade -q pip && pip install -q black && black --fast --check .
+
 build_and_push_container:
   stage: deploy
   script:
diff --git a/app/animals.py b/app/animals.py
old mode 100755
new mode 100644