diff --git a/.github/actions/run-interop-ping-test/action.yml b/.github/actions/run-interop-ping-test/action.yml
index b11b33931..75358902d 100644
--- a/.github/actions/run-interop-ping-test/action.yml
+++ b/.github/actions/run-interop-ping-test/action.yml
@@ -77,6 +77,16 @@ runs:
       run: npm run cache -- load
       shell: bash
 
+    - name: Assert Git tree is clean.
+      working-directory: ${{ steps.find-workdir.outputs.WORK_DIR }}
+      shell: bash
+      run: |
+        if [[ -n "$(git status --porcelain)" ]]; then
+          echo "Git tree is dirty. This means that building an impl generated something that should probably be .gitignore'd"
+          git status
+          exit 1
+        fi
+
     - name: Push the image cache
       if: env.PUSH_CACHE == 'true'
       working-directory: ${{ steps.find-workdir.outputs.WORK_DIR }}