diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index a855f5f3..e52ad74d 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -1,10 +1,12 @@
 name: main
-on: push
+on:
+    pull_request:
+    push:
 jobs:
   build:
     runs-on: ubuntu-latest
     strategy:
-      matrix: 
+      matrix:
         php-versions: [7.2, 7.3, 7.4]
     steps:
     - uses: actions/checkout@v2
@@ -21,7 +23,7 @@ jobs:
       uses: actions/cache@v1
       with:
         path: ${{ steps.composer-cache.outputs.dir }}
-        key: ${{ runner.os }}-composer-${{ hashFiles('**/composer.json') }} 
+        key: ${{ runner.os }}-composer-${{ hashFiles('**/composer.json') }}
         restore-keys: ${{ runner.os }}-composer-
     - name: composer install
       run: composer install --no-interaction --no-ansi --no-progress --no-suggest