diff --git a/cmd/gogh/list.go b/cmd/gogh/list.go
index a57ca8b..de76e53 100644
--- a/cmd/gogh/list.go
+++ b/cmd/gogh/list.go
@@ -38,6 +38,7 @@ var (
 				if err != nil {
 					return err
 				}
+				log.FromContext(ctx).Debugf("found %d projects in %q", len(projects), root)
 				for _, project := range projects {
 					str, err := f.Format(project)
 					if err != nil {
diff --git a/local.go b/local.go
index ca04dac..623390a 100644
--- a/local.go
+++ b/local.go
@@ -7,6 +7,7 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+	"sync"
 
 	"github.com/apex/log"
 	git "github.com/go-git/go-git/v5"
@@ -208,6 +209,8 @@ type LocalWalkOption struct {
 	Query string
 }
 
+var mu sync.Mutex
+
 func (l *LocalController) Walk(
 	ctx context.Context,
 	opt *LocalWalkOption,
@@ -251,6 +254,8 @@ func (l *LocalController) Walk(
 		if opt != nil && !strings.Contains(p.RelPath(), opt.Query) {
 			return nil
 		}
+		mu.Lock()
+		defer mu.Unlock()
 		return walkFn(p)
 	})
 }