diff --git a/foam_sync.ps1 b/foam_sync.ps1
index 06cd4d5..eece326 100644
--- a/foam_sync.ps1
+++ b/foam_sync.ps1
@@ -49,6 +49,7 @@ try {
       Write-Host "Checking trigger..."
       $triggerMatches = $false
       if ($currentTrigger -is [Microsoft.Management.Infrastructure.CimInstance] `
+          -and $null -ne $currentTrigger.RepetitionInterval `
           -and $currentTrigger.RepetitionInterval.TotalMinutes -eq $trigger.RepetitionInterval.TotalMinutes) {
         $triggerMatches = $true
       }