diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 36cd811..1a6176c 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -1,6 +1,12 @@
 name: CI (test)
 
-on: [push]
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
 
 jobs:
   test:
diff --git a/01-ci-lab/app/calculator.py b/01-ci-lab/app/calculator.py
index b11f1ee..6c79abc 100644
--- a/01-ci-lab/app/calculator.py
+++ b/01-ci-lab/app/calculator.py
@@ -5,5 +5,6 @@ def add(a, b):
 def divide(a, b):
     return a / b
 
+
 def divide2(a, b):
     return a / b