diff --git a/.github/workflows/cpp_ubuntu20_04.yml b/.github/workflows/cpp_ubuntu20_04.yml
index d64b6cb..d588868 100644
--- a/.github/workflows/cpp_ubuntu20_04.yml
+++ b/.github/workflows/cpp_ubuntu20_04.yml
@@ -1,5 +1,8 @@
 name: lpp
 on:
+  pull_request:
+    branches:
+      - "master"
   push:
     branches:
       - "master"