diff --git a/Scripts/GUI/Show-ImportExportConfigWindow.ps1 b/Scripts/GUI/Show-ImportExportConfigWindow.ps1
index edcfd6f..ef4a709 100644
--- a/Scripts/GUI/Show-ImportExportConfigWindow.ps1
+++ b/Scripts/GUI/Show-ImportExportConfigWindow.ps1
@@ -33,7 +33,7 @@ function Show-ImportExportConfigWindow {
         [string]$Prompt,
         [string[]]$Categories = @('Applications', 'System Tweaks', 'Deployment Settings'),
         [string[]]$DisabledCategories = @(),
-        [hashtable]$CategoryDetails = @(),
+        [hashtable]$CategoryDetails = @{},
         [string]$ActionLabel = (Get-Translation -Key 'MessageBoxOk')
     )
 
diff --git a/Tests/ParameterDefaults.Tests.ps1 b/Tests/ParameterDefaults.Tests.ps1
new file mode 100644
index 0000000..0cca4be
--- /dev/null
+++ b/Tests/ParameterDefaults.Tests.ps1
@@ -0,0 +1,56 @@
+BeforeAll {
+    # A default value is converted to the parameter's type when the parameter is not supplied. An empty array
+    # cannot be converted to a hashtable, so a [hashtable] parameter with an array default fails at the call that
+    # leaves it out and can sit unnoticed in a rarely used path. (The reverse is fine: PowerShell converts a
+    # hashtable default to a one-element array for [string[]], [object[]] and [array].)
+    function Get-MismatchedParameterDefaults {
+        param([string[]]$Path)
+
+        foreach ($file in $Path) {
+            $tokens = $null
+            $parseErrors = $null
+            $ast = [System.Management.Automation.Language.Parser]::ParseFile($file, [ref]$tokens, [ref]$parseErrors)
+            $parseErrors | Should -BeNullOrEmpty
+
+            foreach ($parameter in $ast.FindAll({ param($node) $node -is [System.Management.Automation.Language.ParameterAst] }, $true)) {
+                $default = $parameter.DefaultValue
+                if ($null -eq $default) { continue }
+
+                $isHashtable = $parameter.StaticType -eq [hashtable]
+                $defaultExpression = $default
+                while ($defaultExpression -is [System.Management.Automation.Language.ParenExpressionAst]) {
+                    $defaultExpression = $defaultExpression.Pipeline.GetPureExpression()
+                }
+                $defaultIsArray = $defaultExpression -is [System.Management.Automation.Language.ArrayExpressionAst] -or
+                    $defaultExpression -is [System.Management.Automation.Language.ArrayLiteralAst]
+
+                if ($isHashtable -and $defaultIsArray) {
+                    '{0}:{1} {2} = {3}' -f (Split-Path $file -Leaf), $parameter.Extent.StartLineNumber, $parameter.Name.Extent.Text, $default.Extent.Text
+                }
+            }
+        }
+    }
+}
+
+Describe 'Parameter default values' {
+    It 'does not give a hashtable parameter an array default' {
+        $root = Join-Path $PSScriptRoot '..'
+        $files = @(Get-ChildItem -LiteralPath (Join-Path $root 'Scripts') -Filter '*.ps1' -File -Recurse | ForEach-Object { $_.FullName })
+        $files += (Join-Path $root 'Win11Debloat.ps1')
+
+        $violations = @(Get-MismatchedParameterDefaults -Path $files)
+
+        $violations | Should -HaveCount 0 -Because ($violations -join '; ')
+    }
+
+    It 'detects a mismatched default' {
+        $sample = Join-Path $TestDrive 'sample.ps1'
+        Set-Content -LiteralPath $sample -Value 'function Test-Sample { param([hashtable]$A = @(), [hashtable]$B = @{}, [string[]]$C = @(), [string[]]$D = @{}, [hashtable]$E = (1, 2)) }'
+
+        $violations = @(Get-MismatchedParameterDefaults -Path @($sample))
+
+        $violations | Should -HaveCount 2
+        $violations | Should -Contain 'sample.ps1:1 $A = @()'
+        $violations | Should -Contain 'sample.ps1:1 $E = (1, 2)'
+    }
+}