diff --git a/doc/31-Changelog.md b/doc/31-Changelog.md
index f86f593..9b32a6e 100644
--- a/doc/31-Changelog.md
+++ b/doc/31-Changelog.md
@@ -20,6 +20,7 @@ Released closed milestones can be found on [GitHub](https://github.com/Icinga/ic
 * [#78](https://github.com/Icinga/icinga-powershell-framework/issues/78) Fix Icinga Agent package fetching for x86 architecture
 * [#79](https://github.com/Icinga/icinga-powershell-framework/issues/79) Fix ConvertTo-Seconds to output valid numeric data with multiple digits
 * [#81](https://github.com/Icinga/icinga-powershell-framework/issues/81), [#82](https://github.com/Icinga/icinga-powershell-framework/issues/82) Fix error on EventLog initialising in case `Icinga for Windows` application is not registered on new machines
+* [#84](https://github.com/Icinga/icinga-powershell-framework/issues/84), Fix conversion of `ConvertTo-Seconds` and `ConvertTo-SecondsFromIcingaThresholds` while the input value is `$null`
 
 ## 1.1.2 (2020-07-01)
 
diff --git a/lib/core/tools/ConvertTo-Seconds.psm1 b/lib/core/tools/ConvertTo-Seconds.psm1
index 59bd7aa..b7ee663 100644
--- a/lib/core/tools/ConvertTo-Seconds.psm1
+++ b/lib/core/tools/ConvertTo-Seconds.psm1
@@ -107,7 +107,7 @@ function ConvertTo-SecondsFromIcingaThresholds()
 
     [string]$Value = [string]::Join(':', $NewContent);
 
-    if ($Value.Contains(':') -eq $FALSE) {
+    if ([string]::IsNullOrEmpty($Value) -eq $FALSE -And $Value.Contains(':') -eq $FALSE) {
         return [convert]::ToDouble($Value);
     }