diff --git a/src/prs.rs b/src/prs.rs
index ed4fe2d..487f320 100644
--- a/src/prs.rs
+++ b/src/prs.rs
@@ -1285,24 +1285,165 @@ async fn guess_pr(
     api: &Forgejo,
 ) -> eyre::Result<forgejo_api::structs::PullRequest> {
     let local_repo = git2::Repository::open(".")?;
-    let head_id = local_repo.head()?.peel_to_commit()?.id();
-    let sha = oid_to_string(head_id);
-    let pr = api
-        .repo_get_commit_pull_request(repo.owner(), repo.name(), &sha)
-        .await?;
-    Ok(pr)
+    let head = local_repo.head()?;
+    eyre::ensure!(head.is_branch(), "head is not on branch");
+    let local_branch = git2::Branch::wrap(head);
+    let remote_branch = local_branch.upstream()?;
+    let remote_head_name = remote_branch
+        .get()
+        .name()
+        .ok_or_eyre("remote branch does not have valid name")?;
+    let remote_head_short = remote_head_name
+        .rsplit_once("/")
+        .map(|(_, b)| b)
+        .unwrap_or(remote_head_name);
+    let this_repo = api.repo_get(repo.owner(), repo.name()).await?;
+
+    // check for PRs on the main branch first
+    let base = this_repo
+        .default_branch
+        .as_deref()
+        .ok_or_eyre("repo does not have default branch")?;
+    if let Ok(pr) = api
+        .repo_get_pull_request_by_base_head(repo.owner(), repo.name(), base, remote_head_short)
+        .await
+    {
+        return Ok(pr);
+    }
+
+    let this_full_name = this_repo
+        .full_name
+        .as_deref()
+        .ok_or_eyre("repo does not have full name")?;
+    let parent_remote_head_name = format!("{this_full_name}:{remote_head_short}");
+
+    if let Some(parent) = this_repo.parent.as_deref() {
+        let (parent_owner, parent_name) = repo_name_from_repo(parent)?;
+        let parent_base = this_repo
+            .default_branch
+            .as_deref()
+            .ok_or_eyre("repo does not have default branch")?;
+        if let Ok(pr) = api
+            .repo_get_pull_request_by_base_head(
+                parent_owner,
+                parent_name,
+                parent_base,
+                &parent_remote_head_name,
+            )
+            .await
+        {
+            return Ok(pr);
+        }
+    }
+
+    // then iterate all branches
+    if let Some(pr) = find_pr_from_branch(repo.owner(), repo.name(), api, remote_head_short).await?
+    {
+        return Ok(pr);
+    }
+
+    if let Some(parent) = this_repo.parent.as_deref() {
+        let (parent_owner, parent_name) = repo_name_from_repo(parent)?;
+
+        if let Some(pr) =
+            find_pr_from_branch(parent_owner, parent_name, api, &parent_remote_head_name).await?
+        {
+            return Ok(pr);
+        }
+    }
+
+    eyre::bail!("could not find PR");
 }
 
-fn oid_to_string(oid: git2::Oid) -> String {
-    let mut s = String::with_capacity(40);
-    for byte in oid.as_bytes() {
-        s.push(
-            char::from_digit((byte & 0xF) as u32, 16).expect("every nibble is a valid hex digit"),
-        );
-        s.push(
-            char::from_digit(((byte >> 4) & 0xF) as u32, 16)
-                .expect("every nibble is a valid hex digit"),
-        );
+async fn find_pr_from_branch(
+    repo_owner: &str,
+    repo_name: &str,
+    api: &Forgejo,
+    head: &str,
+) -> eyre::Result<Option<forgejo_api::structs::PullRequest>> {
+    for page in 1.. {
+        let branch_query = forgejo_api::structs::RepoListBranchesQuery {
+            page: Some(page),
+            limit: Some(30),
+        };
+        let remote_branches = match api
+            .repo_list_branches(repo_owner, repo_name, branch_query)
+            .await
+        {
+            Ok(x) if !x.is_empty() => x,
+            _ => break,
+        };
+
+        let prs = futures::future::try_join_all(
+            remote_branches
+                .into_iter()
+                .map(|branch| check_branch_pair(repo_owner, repo_name, api, branch, head)),
+        )
+        .await?;
+        for pr in prs {
+            if pr.is_some() {
+                return Ok(pr);
+            }
+        }
     }
-    s
+    Ok(None)
 }
+
+async fn check_branch_pair(
+    repo_owner: &str,
+    repo_name: &str,
+    api: &Forgejo,
+    base: forgejo_api::structs::Branch,
+    head: &str,
+) -> eyre::Result<Option<forgejo_api::structs::PullRequest>> {
+    let base_name = base
+        .name
+        .as_deref()
+        .ok_or_eyre("remote branch does not have name")?;
+    match api
+        .repo_get_pull_request_by_base_head(repo_owner, repo_name, base_name, head)
+        .await
+    {
+        Ok(pr) => Ok(Some(pr)),
+        Err(_) => Ok(None),
+    }
+}
+
+fn repo_name_from_repo(repo: &forgejo_api::structs::Repository) -> eyre::Result<(&str, &str)> {
+    let owner = repo
+        .owner
+        .as_ref()
+        .ok_or_eyre("repo does not have owner")?
+        .login
+        .as_deref()
+        .ok_or_eyre("repo owner does not have name")?;
+    let name = repo.name.as_deref().ok_or_eyre("repo does not have name")?;
+    Ok((owner, name))
+}
+
+//async fn guess_pr(
+//    repo: &RepoName,
+//    api: &Forgejo,
+//) -> eyre::Result<forgejo_api::structs::PullRequest> {
+//    let local_repo = git2::Repository::open(".")?;
+//    let head_id = local_repo.head()?.peel_to_commit()?.id();
+//    let sha = oid_to_string(head_id);
+//    let pr = api
+//        .repo_get_commit_pull_request(repo.owner(), repo.name(), &sha)
+//        .await?;
+//    Ok(pr)
+//}
+//
+//fn oid_to_string(oid: git2::Oid) -> String {
+//    let mut s = String::with_capacity(40);
+//    for byte in oid.as_bytes() {
+//        s.push(
+//            char::from_digit((byte & 0xF) as u32, 16).expect("every nibble is a valid hex digit"),
+//        );
+//        s.push(
+//            char::from_digit(((byte >> 4) & 0xF) as u32, 16)
+//                .expect("every nibble is a valid hex digit"),
+//        );
+//    }
+//    s
+//}