diff --git a/routers/web/repo/pull.go b/routers/web/repo/pull.go
index c2208120fcf24..71bc98d13d07c 100644
--- a/routers/web/repo/pull.go
+++ b/routers/web/repo/pull.go
@@ -1395,7 +1395,7 @@ func CleanUpPullRequest(ctx *context.Context) {
 }
 
 func deleteBranch(ctx *context.Context, pr *issues_model.PullRequest, gitRepo *git.Repository) {
-	fullBranchName := pr.HeadRepo.Owner.Name + "/" + pr.HeadBranch
+	fullBranchName := pr.HeadRepo.FullName() + ":" + pr.HeadBranch
 	if err := repo_service.DeleteBranch(ctx.Doer, pr.HeadRepo, gitRepo, pr.HeadBranch); err != nil {
 		switch {
 		case git.IsErrBranchNotExist(err):