diff --git a/.github/workflows/lint-external-links.yml b/.github/workflows/lint-external-links.yml
index aa04a44f0e591..f5417bf9f876a 100644
--- a/.github/workflows/lint-external-links.yml
+++ b/.github/workflows/lint-external-links.yml
@@ -29,8 +29,10 @@ jobs:
 
       - name: Get changed files
         id: changed
+        env:
+          BASE_REF: ${{ github.base_ref }}
         run: |
-          FILES=$(git diff --name-only --diff-filter=AMR origin/${{ github.base_ref }}...HEAD -- '*.md' '*.mdx' || true)
+          FILES=$(git diff --name-only --diff-filter=AMR origin/"${BASE_REF}"...HEAD -- '*.md' '*.mdx' || true)
           if [ -z "$FILES" ]; then
             echo "files=" >> $GITHUB_OUTPUT
             echo "No markdown files changed"