diff --git a/modules/monitoring/library/Monitoring/Plugin/Perfdata.php b/modules/monitoring/library/Monitoring/Plugin/Perfdata.php
index 6c2d89a72..44e377a3e 100644
--- a/modules/monitoring/library/Monitoring/Plugin/Perfdata.php
+++ b/modules/monitoring/library/Monitoring/Plugin/Perfdata.php
@@ -72,20 +72,6 @@ class Perfdata
      */
     protected $criticalThreshold;
 
-    /**
-     * The WARNING threshold as got from the plugin
-     *
-     * @var string
-     */
-    protected $rawWarningThreshold;
-
-    /**
-     * The CRITICAL threshold as got from the plugin
-     *
-     * @var string
-     */
-    protected $rawCriticalThreshold;
-
     /**
      * Create a new Perfdata object based on the given performance data label and value
      *
@@ -321,27 +307,23 @@ class Perfdata
                 }
             /* @noinspection PhpMissingBreakStatementInspection */
             case 3:
-                $this->rawCriticalThreshold = trim($parts[2]);
                 $this->criticalThreshold = self::convert(
-                    ThresholdRange::fromString($this->rawCriticalThreshold),
+                    ThresholdRange::fromString(trim($parts[2])),
                     $this->unit
                 );
                 // Fallthrough
             case 2:
-                $this->rawWarningThreshold = trim($parts[1]);
                 $this->warningThreshold = self::convert(
-                    ThresholdRange::fromString($this->rawWarningThreshold),
+                    ThresholdRange::fromString(trim($parts[1])),
                     $this->unit
                 );
         }
 
         if ($this->warningThreshold === null) {
             $this->warningThreshold = new ThresholdRange();
-            $this->rawWarningThreshold = '';
         }
         if ($this->criticalThreshold === null) {
             $this->criticalThreshold = new ThresholdRange();
-            $this->rawCriticalThreshold = '';
         }
     }
 
@@ -469,14 +451,14 @@ class Perfdata
             $max = $this->warningThreshold->getMax();
             $warn = $max === null ? '∞' : $this->format($max);
         } else {
-            $warn = $this->rawWarningThreshold;
+            $warn = (string) $this->warningThreshold;
         }
 
         if ($this->criticalThreshold->getMin() === null) {
             $max = $this->criticalThreshold->getMax();
             $crit = $max === null ? '∞' : $this->format($max);
         } else {
-            $crit = $this->rawCriticalThreshold;
+            $crit = (string) $this->criticalThreshold;
         }
 
         return array(
diff --git a/modules/monitoring/library/Monitoring/Plugin/ThresholdRange.php b/modules/monitoring/library/Monitoring/Plugin/ThresholdRange.php
index 536dc8f7a..59a9a1fab 100644
--- a/modules/monitoring/library/Monitoring/Plugin/ThresholdRange.php
+++ b/modules/monitoring/library/Monitoring/Plugin/ThresholdRange.php
@@ -29,6 +29,13 @@ class ThresholdRange
      */
     protected $inverted = false;
 
+    /**
+     * The unmodified range as passed to fromString()
+     *
+     * @var string
+     */
+    protected $raw;
+
     /**
      * Create a new instance based on a threshold range conforming to <https://nagios-plugins.org/doc/guidelines.html>
      *
@@ -39,6 +46,7 @@ class ThresholdRange
     public static function fromString($rawRange = '')
     {
         $range = new static();
+        $range->raw = $rawRange;
 
         if ($rawRange === '') {
             return $range;
@@ -166,13 +174,6 @@ class ThresholdRange
      */
     public function __toString()
     {
-        if ($this->min === null) {
-            $res = '~:';
-        } else {
-            $res = $this->min === 0.0 ? '' : $this->min . ':';
-        }
-        $res .= $this->max === null ? '' : $this->max;
-
-        return ($this->inverted ? '@' : '') . (empty($res) ? '0:' : $res);
+        return (string) $this->raw;
     }
 }