diff --git a/tools/migrate_repo_names.go b/tools/migrate_repo_names.go
new file mode 100644
index 0000000..4240ae4
--- /dev/null
+++ b/tools/migrate_repo_names.go
@@ -0,0 +1,116 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"log"
+	"regexp"
+	"time"
+
+	"github.com/boltdb/bolt"
+	"github.com/gojp/goreportcard/handlers"
+)
+
+const (
+	dbPath     string = "goreportcard.db"
+	repoBucket string = "repos"
+	metaBucket string = "meta"
+)
+
+func main() {
+	oldFormat := regexp.MustCompile(`^([a-zA-Z0-9\-_]+)/([a-zA-Z0-9\-_]+)$`)
+
+	db, err := bolt.Open(handlers.DBPath, 0600, &bolt.Options{Timeout: 1 * time.Second})
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer db.Close()
+	err = db.Update(func(tx *bolt.Tx) error {
+		rb := tx.Bucket([]byte(repoBucket))
+		if rb == nil {
+			return fmt.Errorf("repo bucket not found")
+		}
+		toDelete := []string{}
+		rb.ForEach(func(k, v []byte) error {
+			sk := string(k)
+			m := oldFormat.FindStringSubmatch(sk)
+			if m != nil {
+				err = rb.Put([]byte("github.com/"+sk), v)
+				if err != nil {
+					return err
+				}
+				toDelete = append(toDelete, string(v))
+			}
+			return nil
+		})
+		for i := range toDelete {
+			err = rb.Delete([]byte(toDelete[i]))
+			if err != nil {
+				return err
+			}
+		}
+
+		// finally update the high scores
+		mb := tx.Bucket([]byte(metaBucket))
+		if mb == nil {
+			return fmt.Errorf("meta bucket not found")
+		}
+
+		scoreBytes := mb.Get([]byte("scores"))
+		if scoreBytes == nil {
+			scoreBytes, _ = json.Marshal([]scoreHeap{})
+		}
+		scores := &scoreHeap{}
+		json.Unmarshal(scoreBytes, scores)
+		for i := range *scores {
+			m := oldFormat.FindStringSubmatch((*scores)[i].Repo)
+			if m != nil {
+				(*scores)[i] = scoreItem{
+					Repo:  "github.com/" + (*scores)[i].Repo,
+					Score: (*scores)[i].Score,
+					Files: (*scores)[i].Files,
+				}
+			}
+		}
+		scoreBytes, err = json.Marshal(scores)
+		if err != nil {
+			return err
+		}
+		err = mb.Put([]byte("scores"), scoreBytes)
+		if err != nil {
+			return err
+		}
+
+		return nil
+	})
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+type scoreItem struct {
+	Repo  string  `json:"repo"`
+	Score float64 `json:"score"`
+	Files int     `json:"files"`
+}
+
+// An scoreHeap is a min-heap of ints.
+type scoreHeap []scoreItem
+
+func (h scoreHeap) Len() int           { return len(h) }
+func (h scoreHeap) Less(i, j int) bool { return h[i].Score < h[j].Score }
+func (h scoreHeap) Swap(i, j int)      { h[i], h[j] = h[j], h[i] }
+
+func (h *scoreHeap) Push(x interface{}) {
+	// Push and Pop use pointer receivers because they modify the slice's length,
+	// not just its contents.
+	*h = append(*h, x.(scoreItem))
+}
+
+func (h *scoreHeap) Pop() interface{} {
+	old := *h
+	n := len(old)
+	x := old[n-1]
+	*h = old[0 : n-1]
+	return x
+}