diff --git a/wo/cli/plugins/stack_upgrade.py b/wo/cli/plugins/stack_upgrade.py
index ab12b55..401ca44 100644
--- a/wo/cli/plugins/stack_upgrade.py
+++ b/wo/cli/plugins/stack_upgrade.py
@@ -282,7 +282,7 @@ class WOStackUpgradeController(CementBaseController):
                 if pargs.ngxblocker:
                     WOFileUtils.chmod(
                         self, '/usr/local/sbin/update-ngxblocker', 0o700)
-                    WOShellExec.chmod(
+                    WOShellExec.shellexec(
                         self, '/usr/local/sbin/update-ngxblocker -nq'
                     )