diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index a03c7242..12676c2a 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -25,6 +25,11 @@ jobs:
       GITHUB_PAT: ${{ secrets.GITHUB_TOKEN }}
 
     steps:
+      - name: Tests will fail on PRs from forks
+        if: github.event.pull_request.head.repo.full_name != github.repository
+        run: |
+          echo Tests require pull requests be submitted from branches in the main repository
+          exit 1 
       - uses: actions/checkout@v4
         with:
             fetch-depth: 3