diff --git a/certy.ps1 b/certy.ps1
index 095e099..7696fad 100644
--- a/certy.ps1
+++ b/certy.ps1
@@ -72,7 +72,7 @@ function Get-FilePreview {
 
 function Get-CommonZoneFromHosts {
     param([string[]]$Hosts)
-    $fqdnHosts = $Hosts | Where-Object { $_ -and $_.Contains(".") }
+    $fqdnHosts = @($Hosts | Where-Object { $_ -and $_.Contains(".") })
     if (-not $fqdnHosts -or $fqdnHosts.Count -eq 0) { return "" }
 
     $commonSuffix = $null
@@ -852,7 +852,7 @@ $replicationEnabledBox.Add_CheckedChanged({
 $filePreviewBtn.Add_Click({
     $path = $fileBox.Text.Trim()
     if ([string]::IsNullOrWhiteSpace($path)) {
-        $previewHosts = Split-List $hostsBox.Text
+        $previewHosts = @(Split-List $hostsBox.Text)
         if ($previewHosts.Count -gt 0) {
             $filePreviewBox.Text = ($previewHosts | Select-Object -First 200) -join [Environment]::NewLine
             return