diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index bed4805..f2bcc4c 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -2,7 +2,9 @@ name: run tests
 
 on:
   push:
+    branches: [ master ]
   pull_request:
+    branches: [ master ]
   schedule:
     - cron: '0 12 * * 0'  # run once a week on Sunday
 
@@ -41,11 +43,11 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install tox coveralls
+        pip install tox coveralls coverage-python-version
     - name: Test
       run: tox -e ${{ matrix.config[2] }}
     - name: Coverage
-      if: matrix.config[1] == 'coverage'
+      if: matrix.config[2] == 'coverage'
       run: coveralls
       env:
         GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}