diff --git a/modules/monitoring/library/Monitoring/Plugin/Perfdata.php b/modules/monitoring/library/Monitoring/Plugin/Perfdata.php
index bafb49f49..476354a66 100644
--- a/modules/monitoring/library/Monitoring/Plugin/Perfdata.php
+++ b/modules/monitoring/library/Monitoring/Plugin/Perfdata.php
@@ -474,7 +474,7 @@ class Perfdata
             $html ? '<b>%s %s</b> (%s%%)' : '%s %s (%s%%)',
             htmlspecialchars($this->getLabel()),
             $this->format($this->value),
-            number_format($this->getPercentage(), 2)
+            number_format($this->getPercentage() ?? 0, 2)
         );
     }