diff --git a/README.md b/README.md
index edb66b5..a92edcb 100644
--- a/README.md
+++ b/README.md
@@ -6,20 +6,34 @@ A GitHub Action that checks the commits of the current PR and fails if it contai
 
 ```yml
 name: Check signed commits in PR 
-on: pull_request
+on: pull_request_target
 
 jobs:
-  build:
-    name: Check signed commits in PR 
+  check-signed-commits:
+    name: Check signed commits in PR
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      pull-requests: write
     steps:
-      - name: Check out code
-        uses: actions/checkout@v4
-
       - name: Check signed commits in PR
         uses: 1Password/check-signed-commits-action@v1
 ```
 
+## `pull_request_target` vs. `pull_request`
+
+Workflows containing this action can be configured to run both on [`pull_request`](https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#pull_request) events as on [`pull_request_target`](https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#pull_request_target) events.
+
+The reason to prefer `pull_request_target` over `pull_request` is to allow the action to post comments on external PRs created from forks. The GitHub token that comes with the regular `pull_request` event does not support commenting on PRs in the upstream repo.
+
+ When using `pull_request_target`, make sure to set the right permissions in the workflow:
+
+```yml
+permissions:
+  contents: read
+  pull-requests: write
+```
+
 ## Change PR Comment
 
 The comment that will be placed in the PR upon detecting unsigned commits can be changed using the `comment` field:
diff --git a/action.yml b/action.yml
index b6c8400..8f96730 100644
--- a/action.yml
+++ b/action.yml
@@ -58,21 +58,16 @@ runs:
         GITHUB_TOKEN: ${{ inputs.token }}
         COMMENT_TEXT: ${{ inputs.comment }}
         COMMENTS_URL: ${{ github.event.pull_request.comments_url }}
+        COMMITS_URL: ${{ github.event.pull_request.commits_url }}
       run: |
-        # Escape double quotes and newlines
-        COMMENT_TEXT="$(echo "$COMMENT_TEXT" | sed 's/"/\\"/g' | awk '{printf "%s\\n", $0}')"
-
-        GITHUB_PR=$(echo $GITHUB_REF | sed -n 's/refs\/pull\/\([0-9]*\)\/merge/\1/p')
-        if [[ -z "$GITHUB_PR" ]]; then
-          echo "No PR found to scan for commits."
-          exit 0
-        fi
-
-        unsigned_commits="$(curl -s -H "Authorization: token $GITHUB_TOKEN" "${GITHUB_API_URL:-https://api.github.com}/repos/$GITHUB_REPOSITORY/pulls/$GITHUB_PR/commits" | jq '.[] | select(.commit.verification.verified == false) | .commit.message')"
+        unsigned_commits="$(curl -s -H "Authorization: token $GITHUB_TOKEN" "$COMMITS_URL" | jq '.[] | select(.commit.verification.verified == false) | .commit.message')"
         if [[ -n "$unsigned_commits" ]]; then
           echo "Found unsigned commits:"
           echo "$unsigned_commits"
 
+          # Escape double quotes and newlines in comment
+          COMMENT_TEXT="$(echo "$COMMENT_TEXT" | sed 's/"/\\"/g' | awk '{printf "%s\\n", $0}')"
+
           curl -X POST $COMMENTS_URL \
             -H "Content-Type: application/json" \
             -H "Authorization: token $GITHUB_TOKEN" \