diff --git a/.github/workflows/auto-fill-pr.yml b/.github/workflows/auto-fill-pr.yml
index db3cbf1..d5e69e0 100644
--- a/.github/workflows/auto-fill-pr.yml
+++ b/.github/workflows/auto-fill-pr.yml
@@ -198,11 +198,30 @@ jobs:
             const claudeSuccess = '${{ steps.claude.outputs.success }}' === 'true';
             const testingSuccess = '${{ steps.testing.outputs.success }}' === 'true';
 
+            // Get PR number - context.payload.pull_request is undefined for workflow_call
+            let prNumber;
+            if (context.payload.pull_request) {
+              prNumber = context.payload.pull_request.number;
+            } else {
+              const ref = context.ref.replace('refs/heads/', '');
+              const { data: prs } = await github.rest.pulls.list({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                state: 'open',
+                head: `${context.repo.owner}:${ref}`
+              });
+              if (prs.length === 0) {
+                core.warning('No open PR found for this branch, skipping PR update');
+                return;
+              }
+              prNumber = prs[0].number;
+            }
+
             // Get existing PR body
             const { data: pr } = await github.rest.pulls.get({
               owner: context.repo.owner,
               repo: context.repo.repo,
-              pull_number: context.payload.pull_request.number
+              pull_number: prNumber
             });
             const existingBody = pr.body || '';
 
@@ -320,7 +339,7 @@ jobs:
               await github.rest.pulls.update({
                 owner: context.repo.owner,
                 repo: context.repo.repo,
-                pull_number: context.payload.pull_request.number,
+                pull_number: prNumber,
                 body: newBody
               });
             }
\ No newline at end of file