diff --git a/services/pull/pull.go b/services/pull/pull.go
index bba86ab00f..fb631af08a 100644
--- a/services/pull/pull.go
+++ b/services/pull/pull.go
@@ -629,6 +629,8 @@ func (errs errlist) Error() string {
 	return ""
 }
 
+var _ error = &errlist{}
+
 // RetargetBranchPulls change target branch for all pull requests whose base branch is the branch
 // Both branch and targetBranch must be in the same repo (for security reasons)
 func RetargetBranchPulls(ctx context.Context, doer *user_model.User, repoID int64, branch, targetBranch string) error {
@@ -716,7 +718,10 @@ func ClosePullsCausedByBranchDeleted(ctx context.Context, doer *user_model.User,
 			}
 		}
 	}
-	return errs
+	if len(errs) > 0 {
+		return errs
+	}
+	return nil
 }
 
 // CloseRepoBranchesPulls close all pull requests which head branches are in the given repository, but only whose base repo is not in the given repository
diff --git a/services/repository/push.go b/services/repository/push.go
index ef33200d3e..e18c6685e3 100644
--- a/services/repository/push.go
+++ b/services/repository/push.go
@@ -282,7 +282,7 @@ func pushUpdates(optsList []*repo_module.PushUpdateOptions) error {
 					}
 				}
 
-				if err = pull_service.ClosePullsCausedByBranchDeleted(ctx, pusher, repo.ID, branch); err != nil {
+				if err := pull_service.ClosePullsCausedByBranchDeleted(ctx, pusher, repo.ID, branch); err != nil {
 					// close all related pulls
 					log.Error("close related pull request failed: %v", err)
 				}