diff --git a/lib/core/tools/ConvertTo-Integer.psm1 b/lib/core/tools/ConvertTo-Integer.psm1
new file mode 100644
index 0000000..8c195b8
--- /dev/null
+++ b/lib/core/tools/ConvertTo-Integer.psm1
@@ -0,0 +1,65 @@
+<#
+.SYNOPSIS
+   Helper function to convert values to integer if possible
+.DESCRIPTION
+   Converts an input value to integer if possible in any way. Otherwise it will return the object unmodified
+
+   More Information on https://github.com/Icinga/icinga-powershell-framework
+.FUNCTIONALITY
+   Converts an input value to integer if possible in any way. Otherwise it will return the object unmodified
+.PARAMETER Value
+   Any value/object is analysed and if possible converted to an integer
+.INPUTS
+   System.Object
+.OUTPUTS
+   System.Integer
+
+.LINK
+   https://github.com/Icinga/icinga-powershell-framework
+.NOTES
+#>
+
+function ConvertTo-Integer()
+{
+    param (
+        $Value,
+        [switch]$NullAsEmpty
+    );
+
+    if ($null -eq $Value) {
+        if ($NullAsEmpty) {
+            return '';
+        }
+
+        return 0;
+    }
+
+    if ([string]::IsNullOrEmpty($Value)) {
+        if ($NullAsEmpty) {
+            return '';
+        }
+
+        return 0;
+    }
+
+    if ((Test-Numeric $Value)) {
+        return $Value;
+    }
+
+    $Type = $value.GetType().Name;
+
+    if ($Type -eq 'GpoBoolean' -Or $Type -eq 'Boolean' -Or $Type -eq 'SwitchParameter') {
+        return [int]$Value;
+    }
+
+    if ($Type -eq 'String') {
+        if ($Value.ToLower() -eq 'true' -Or $Value.ToLower() -eq 'yes' -Or $Value.ToLower() -eq 'y') {
+            return 1;
+        }
+        if ($Value.ToLower() -eq 'false' -Or $Value.ToLower() -eq 'no' -Or $Value.ToLower() -eq 'n') {
+            return 0;
+        }
+    }
+    
+    return $Value;
+}
diff --git a/lib/icinga/plugin/New-IcingaCheck.psm1 b/lib/icinga/plugin/New-IcingaCheck.psm1
index 89d8bf7..b7be7a9 100644
--- a/lib/icinga/plugin/New-IcingaCheck.psm1
+++ b/lib/icinga/plugin/New-IcingaCheck.psm1
@@ -147,6 +147,8 @@ function New-IcingaCheck()
             );
         }
 
+        $this.warning = $warning;
+
         return $this;
     }
 
@@ -161,6 +163,8 @@ function New-IcingaCheck()
             );
         }
 
+        $this.warning = $warning;
+
         return $this;
     }
 
@@ -175,6 +179,8 @@ function New-IcingaCheck()
             );
         }
 
+        $this.warning = $warning;
+
         return $this;
     }
 
@@ -189,6 +195,8 @@ function New-IcingaCheck()
             );
         }
 
+        $this.warning = $warning;
+
         return $this;
     }
 
@@ -203,6 +211,8 @@ function New-IcingaCheck()
             );
         }
 
+        $this.warning = [string]::Format('{0}:{1}', $min, $max);
+
         return $this;
     }
 
@@ -217,6 +227,8 @@ function New-IcingaCheck()
             );
         }
 
+        $this.warning = [string]::Format('{0}:{1}', $min, $max);
+
         return $this;
     }
 
@@ -231,6 +243,8 @@ function New-IcingaCheck()
             );
         }
 
+        $this.warning = $warning;
+
         return $this;
     }
 
@@ -245,6 +259,8 @@ function New-IcingaCheck()
             );
         }
 
+        $this.warning = $warning;
+
         return $this;
     }
 
@@ -259,6 +275,8 @@ function New-IcingaCheck()
             );
         }
 
+        $this.warning = $warning;
+
         return $this;
     }
 
@@ -273,6 +291,8 @@ function New-IcingaCheck()
             );
         }
 
+        $this.warning = $warning;
+
         return $this;
     }
 
@@ -329,6 +349,8 @@ function New-IcingaCheck()
             );
         }
 
+        $this.critical = $critical;
+
         return $this;
     }
 
@@ -343,6 +365,8 @@ function New-IcingaCheck()
             );
         }
 
+        $this.critical = $critical;
+
         return $this;
     }
 
@@ -357,6 +381,8 @@ function New-IcingaCheck()
             );
         }
 
+        $this.critical = $critical;
+
         return $this;
     }
 
@@ -371,6 +397,8 @@ function New-IcingaCheck()
             );
         }
 
+        $this.critical = $critical;
+
         return $this;
     }
 
@@ -385,6 +413,8 @@ function New-IcingaCheck()
             );
         }
 
+        $this.critical = [string]::Format('{0}:{1}', $min, $max);
+
         return $this;
     }
 
@@ -399,6 +429,8 @@ function New-IcingaCheck()
             );
         }
 
+        $this.critical = [string]::Format('{0}:{1}', $min, $max);
+
         return $this;
     }
 
@@ -413,6 +445,8 @@ function New-IcingaCheck()
             );
         }
 
+        $this.critical = $critical;
+
         return $this;
     }
 
@@ -427,6 +461,8 @@ function New-IcingaCheck()
             );
         }
 
+        $this.critical = $critical;
+
         return $this;
     }
 
@@ -441,6 +477,8 @@ function New-IcingaCheck()
             );
         }
 
+        $this.critical = $critical;
+
         return $this;
     }
 
@@ -455,6 +493,8 @@ function New-IcingaCheck()
             );
         }
 
+        $this.critical = $critical;
+
         return $this;
     }
 
@@ -721,14 +761,17 @@ function New-IcingaCheck()
 
         $this.completed    = $TRUE;
         [string]$LabelName = (Format-IcingaPerfDataLabel $this.name);
+        $value             = ConvertTo-Integer -Value $this.value -NullAsEmpty;
+        $warning           = ConvertTo-Integer -Value $this.warning -NullAsEmpty;
+        $critical          = ConvertTo-Integer -Value $this.critical -NullAsEmpty;
 
         $perfdata = @{
             'label'    = $LabelName;
             'perfdata' = '';
             'unit'     = $this.unit;
-            'value'    = (Format-IcingaPerfDataValue $this.value);
-            'warning'  = (Format-IcingaPerfDataValue $this.warning);
-            'critical' = (Format-IcingaPerfDataValue $this.critical);
+            'value'    = (Format-IcingaPerfDataValue $value);
+            'warning'  = (Format-IcingaPerfDataValue $warning);
+            'critical' = (Format-IcingaPerfDataValue $critical);
             'minimum'  = (Format-IcingaPerfDataValue $this.minimum);
             'maximum'  = (Format-IcingaPerfDataValue $this.maximum);
             'package'  = $FALSE;