diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 07d5978..0893dbf 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -18,13 +18,20 @@ jobs:
         id: get_diff
         shell: bash
         env:
+          DEFAULT_BRANCH: "${{ github.event.repository.default_branch }}"
           PULL_REQUEST_HEAD_REF: "${{ github.event.pull_request.head.ref }}"
         run: |-
-          git fetch origin "${{ env.PULL_REQUEST_HEAD_REF }}:${{ env.PULL_REQUEST_HEAD_REF }}"
-          git checkout "${{ env.PULL_REQUEST_HEAD_REF }}"
-          git diff "origin/${{ env.PULL_REQUEST_HEAD_REF }}" > "diff.txt"
+          # Fetch the default branch
+          git fetch origin "${{ env.DEFAULT_BRANCH }}"
+          # Exclude png files from diff
+          git diff "origin/${{ env.DEFAULT_BRANCH }}" ":(exclude)*.png" > "diff.txt"
+          # Put multi-line string into an environment variable
           # shellcheck disable=SC2086
-          echo "diff=$(cat "diff.txt")" >> $GITHUB_ENV
+          {
+            echo "pull_request_diff<<EOF";
+            cat "diff.txt";
+            echo 'EOF';
+          } >> $GITHUB_OUTPUT
 
       - name: Groq Code Review
         uses: rajsinghparihar/llm-code-review@v0.0.1-groq