diff --git a/playbook/scripts/preflight.ps1 b/playbook/scripts/preflight.ps1
index a6ab3b3..825f006 100755
--- a/playbook/scripts/preflight.ps1
+++ b/playbook/scripts/preflight.ps1
@@ -81,7 +81,38 @@ try {
     if (-not (Test-Path $catalogue)) {
         Warn "HardwareDriver.json not found at $catalogue - cannot check drivers."
     } else {
-        $entries = Get-Content $catalogue -Raw | ConvertFrom-Json
+        # NOT ConvertFrom-Json. HardwareDriver.json carries both casings of the
+        # same fields - "fileName" and "FileName", "destinationDir" and
+        # "DestinationDir". Windows PowerShell 5.1 (which is what WinPE runs)
+        # treats object keys case-insensitively and throws:
+        #   "cannot convert the JSON string because a dictionary that was
+        #    converted from the string contains the duplicated keys 'FileName'
+        #    and 'FileName'"
+        # -AsHashtable would handle it but that is PowerShell 6+. So pull the
+        # four fields we need out of each entry by text instead. Prefers the
+        # lowercase key, falls back to the capitalised one.
+        $raw = Get-Content $catalogue -Raw
+        $entries = @()
+        foreach ($chunk in ([regex]::Split($raw, '\}\s*,\s*\{'))) {
+            $get = {
+                param($names)
+                foreach ($n in $names) {
+                    $m = [regex]::Match($chunk, '"' + $n + '"\s*:\s*"((?:[^"\\]|\\.)*)"')
+                    if ($m.Success) { return $m.Groups[1].Value -replace '\\\\', '\' }
+                }
+                return ''
+            }
+            $e = [pscustomobject]@{
+                modelswminame  = (& $get @('modelswminame','models'))
+                family         = (& $get @('family'))
+                fileName       = (& $get @('fileName','FileName'))
+                destinationDir = (& $get @('destinationDir','DestinationDir'))
+            }
+            if ($e.modelswminame) { $entries += $e }
+        }
+        if (-not $entries.Count) {
+            Warn "Could not extract any entries from $catalogue - driver check skipped."
+        }
         $family = ''
         if ($model.ToUpper().Contains('LATITUDE'))  { $family = 'Latitude' }
         if ($model.ToUpper().Contains('OPTIPLEX'))  { $family = 'Optiplex' }