diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index ea05295..3941425 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -4,6 +4,9 @@ on:
   push:
     paths:
       - '*.py'
+  pull_request:
+    # The branches below must be a subset of the branches above
+    branches: [ "master" ]
 
 jobs:
   mypy: