diff --git a/models/repo/release.go b/models/repo/release.go
index 663d310bc0..b4637665ab 100644
--- a/models/repo/release.go
+++ b/models/repo/release.go
@@ -161,6 +161,11 @@ func UpdateRelease(ctx context.Context, rel *Release) error {
 	return err
 }
 
+func UpdateReleaseNumCommits(ctx context.Context, rel *Release) error {
+	_, err := db.GetEngine(ctx).ID(rel.ID).Cols("num_commits").Update(rel)
+	return err
+}
+
 // AddReleaseAttachments adds a release attachments
 func AddReleaseAttachments(ctx context.Context, releaseID int64, attachmentUUIDs []string) (err error) {
 	// Check attachments
diff --git a/services/context/repo.go b/services/context/repo.go
index 5b18e0d14e..acf829abee 100644
--- a/services/context/repo.go
+++ b/services/context/repo.go
@@ -938,6 +938,18 @@ func RepoRefByType(detectRefType git.RefType) func(*Context) {
 				ctx.ServerError("GetRelease", err)
 				return
 			}
+			// for mirror tags, the number of commist may not be set
+			if rel.NumCommits <= 0 {
+				rel.NumCommits, err = ctx.Repo.GetCommitsCount()
+				if err != nil {
+					ctx.ServerError("GetCommitsCount", err)
+					return
+				}
+				if err := repo_model.UpdateReleaseNumCommits(ctx, rel); err != nil {
+					ctx.ServerError("UpdateReleaseNumCommits", err)
+					return
+				}
+			}
 			ctx.Repo.CommitsCount = rel.NumCommits
 		} else {
 			ctx.Repo.CommitsCount, err = ctx.Repo.GetCommitsCount()