diff --git a/knotserver/internal.go b/knotserver/internal.go
index 625a72e8..bb08faf9 100644
--- a/knotserver/internal.go
+++ b/knotserver/internal.go
@@ -300,6 +300,11 @@ func (h *InternalHandle) insertRefUpdate(line git.PostReceiveLine, gitUserDid, o
 			return fmt.Errorf("failed to open git repo at ref %s: %w", line.Ref, err)
 		}
 
+		err = h.ensureDefaultBranchIsSet(gr, line)
+		if err != nil {
+			h.l.Error("attempted to ensure default branch is set on repo", "error", err)
+		}
+
 		meta, err := gr.RefUpdateMeta(line)
 		if err != nil {
 			return fmt.Errorf("failed to get ref update metadata: %w", err)
@@ -323,6 +328,28 @@ func (h *InternalHandle) insertRefUpdate(line git.PostReceiveLine, gitUserDid, o
 	return h.db.InsertEvent(event, h.n)
 }
 
+func (h *InternalHandle) ensureDefaultBranchIsSet(gr *git.GitRepo, line git.PostReceiveLine) error {
+	mainBranch, err := gr.FindMainBranch()
+	if err != nil {
+		return err
+	}
+
+	// if main branch is HEAD it means that this is the first push to the repo and the configured default
+	// branch for the knot doesn't match the branch that was just pushed
+	if mainBranch != "HEAD" {
+		return nil
+	}
+
+	defaultBranch := strings.ReplaceAll(line.Ref, "refs/heads/", "")
+	err = gr.SetDefaultBranch(defaultBranch)
+	if err != nil {
+		return fmt.Errorf("setting detault branch: %w", err)
+	}
+	h.l.Info("set default branch to " + defaultBranch)
+
+	return nil
+}
+
 func (h *InternalHandle) triggerPipeline(
 	clientMsgs *[]string,
 	line git.PostReceiveLine,