diff --git a/tools/build/build-installer.ps1 b/tools/build/build-installer.ps1
index 65497aeeaa..2d93821794 100644
--- a/tools/build/build-installer.ps1
+++ b/tools/build/build-installer.ps1
@@ -3,14 +3,7 @@
 Build and package PowerToys (CmdPal and installer) for a specific platform and configuration LOCALLY.
 
 .DESCRIPTION
-This script automates the end-to-end build and packaging process for PowerToys, including:
-- Restoring and building all necessary solutions (CmdPal, BugReportTool, etc.)
-- Cleaning up old output
-- Signing generated .msix packages
-- Building the WiX v5 (VNext) MSI and bootstrapper installers
-
-It is designed to work in local development.
-The cert used to sign the packages is generated by 
+Builds and packages PowerToys (CmdPal and installer) locally. Handles solution build, signing, and WiX installer generation.
 
 .PARAMETER Platform
 Specifies the target platform for the build (e.g., 'arm64', 'x64'). Default is 'x64'.
@@ -45,11 +38,23 @@ Runs the pipeline for x64 Release with machine-wide installer.
 #>
 
 param (
-    [string]$Platform = '',
+    [string]$Platform = 'x64',
     [string]$Configuration = 'Release',
-    [string]$PerUser = 'true'
+    [string]$PerUser = 'true',
+    [switch]$Clean,
+    [switch]$Help
 )
 
+if ($Help) {
+    Write-Host "Usage: .\build-installer.ps1 [-Platform <x64|arm64>] [-Configuration <Release|Debug>] [-PerUser <true|false>] [-Clean]"
+    Write-Host "  -Platform       Target platform (default: auto-detect or x64)"
+    Write-Host "  -Configuration  Build configuration (default: Release)"
+    Write-Host "  -PerUser        Build per-user installer (default: true)"
+    Write-Host "  -Clean          Clean output directories before building"
+    Write-Host "  -Help           Show this help message"
+    exit 0
+}
+
 # Ensure helpers are available
 . "$PSScriptRoot\build-common.ps1"
 
@@ -94,13 +99,33 @@ Write-Host ("[PIPELINE] Start | Platform={0} Configuration={1} PerUser={2}" -f $
 Write-Host ''
 
 $cmdpalOutputPath = Join-Path $repoRoot "$Platform\$Configuration\WinUI3Apps\CmdPal"
+$buildOutputPath = Join-Path $repoRoot "$Platform\$Configuration"
 
-if (Test-Path $cmdpalOutputPath) {
-    Write-Host "[CLEAN] Removing previous output: $cmdpalOutputPath"
-    Remove-Item $cmdpalOutputPath -Recurse -Force -ErrorAction Ignore
+if ($Clean) {
+    if (Test-Path $cmdpalOutputPath) {
+        Write-Host "[CLEAN] Removing previous output: $cmdpalOutputPath"
+        Remove-Item $cmdpalOutputPath -Recurse -Force -ErrorAction Ignore
+    }
+    if (Test-Path $buildOutputPath) {
+        Write-Host "[CLEAN] Removing previous build output: $buildOutputPath"
+        Remove-Item $buildOutputPath -Recurse -Force -ErrorAction Ignore
+    }
+    
+    Write-Host "[CLEAN] Cleaning all build artifacts (git clean -Xfd)..."
+    Push-Location $repoRoot
+    try {
+        git clean -Xfd | Out-Null
+    } catch {
+        Write-Warning "[CLEAN] git clean failed: $_"
+    } finally {
+        Pop-Location
+    }
+
+    Write-Host "[CLEAN] Cleaning solution (msbuild /t:Clean)..."
+    RunMSBuild 'PowerToys.slnx' '/t:Clean' $Platform $Configuration
 }
 
-$commonArgs = '/p:CIBuild=true'
+$commonArgs = '/p:CIBuild=true /p:IsPipeline=true'
 # No local projects found (or continuing) - build full solution and tools
 RestoreThenBuild 'PowerToys.slnx' $commonArgs $Platform $Configuration
 
@@ -133,18 +158,31 @@ if (Test-Path $dscScriptPath) {
 RestoreThenBuild 'tools\BugReportTool\BugReportTool.sln' $commonArgs $Platform $Configuration
 RestoreThenBuild 'tools\StylesReportTool\StylesReportTool.sln' $commonArgs $Platform $Configuration
 
-Write-Host '[CLEAN] installer (keep *.exe)'
-Push-Location $repoRoot
-try {
-    git clean -xfd -e '*.exe' -- .\installer\ | Out-Null
-} finally {
-    Pop-Location
+if ($Clean) {
+    Write-Host '[CLEAN] installer (keep *.exe)'
+    Push-Location $repoRoot
+    try {
+        git clean -xfd -e '*.exe' -- .\installer\ | Out-Null
+    } finally {
+        Pop-Location
+    }
 }
 
 RunMSBuild 'installer\PowerToysSetup.slnx' "$commonArgs /t:restore /p:RestorePackagesConfig=true" $Platform $Configuration
 
 RunMSBuild 'installer\PowerToysSetup.slnx' "$commonArgs /m /t:PowerToysInstallerVNext /p:PerUser=$PerUser" $Platform $Configuration
 
+# Fix: WiX v5 locally puts the MSI in an 'en-us' subfolder, but the Bootstrapper expects it in the root of UserSetup/MachineSetup.
+# We move it up one level to match expectations.
+$setupType = if ($PerUser -eq 'true') { 'UserSetup' } else { 'MachineSetup' }
+$msiParentDir = Join-Path $repoRoot "installer\PowerToysSetupVNext\$Platform\$Configuration\$setupType"
+$msiEnUsDir = Join-Path $msiParentDir "en-us"
+
+if (Test-Path $msiEnUsDir) {
+    Write-Host "[FIX] Moving MSI files from $msiEnUsDir to $msiParentDir"
+    Get-ChildItem -Path $msiEnUsDir -Filter *.msi | Move-Item -Destination $msiParentDir -Force
+}
+
 RunMSBuild 'installer\PowerToysSetup.slnx' "$commonArgs /m /t:PowerToysBootstrapperVNext /p:PerUser=$PerUser" $Platform $Configuration
 
 Write-Host '[PIPELINE] Completed'