diff --git a/.github/workflows/auto-merge.yaml b/.github/workflows/auto-merge.yaml
index aa8fdcc..f0ef235 100644
--- a/.github/workflows/auto-merge.yaml
+++ b/.github/workflows/auto-merge.yaml
@@ -2,10 +2,15 @@ name: Enable auto-merge
 
 on:
   pull_request:
-    types: [opened, ready_for_review, reopened]
+    types: [opened, ready_for_review, reopened, synchronize]
     branches: [main]
 
+concurrency:
+  group: enable-auto-merge-${{ github.event.pull_request.number }}
+  cancel-in-progress: true
+
 permissions:
+  contents: write
   pull-requests: write
 
 jobs:
@@ -28,4 +33,12 @@ jobs:
             echo "auto-merge already enabled"
             exit 0
           fi
-          gh pr merge "$PR" --repo "$REPO" --auto
+          if ! out=$(gh pr merge "$PR" --repo "$REPO" --auto 2>&1); then
+            echo "$out"
+            if [ "$(gh pr view "$PR" --repo "$REPO" --json autoMergeRequest --jq '.autoMergeRequest != null')" = "true" ]; then
+              echo "auto-merge already enabled"
+              exit 0
+            fi
+            exit 1
+          fi
+          printf '%s\n' "$out"