diff --git a/scripts/build-boringtun-win.ps1 b/scripts/build-boringtun-win.ps1
new file mode 100644
index 0000000..5b3e637
--- /dev/null
+++ b/scripts/build-boringtun-win.ps1
@@ -0,0 +1,110 @@
+#Requires -Version 5.1
+<#
+.SYNOPSIS
+    Build boringtun (Cloudflare WireGuard FFI library) for Windows.
+
+.DESCRIPTION
+    Clones or updates the boringtun repository, builds it with Cargo in
+    release mode, and copies the resulting static library to deps/boringtun/.
+
+.PARAMETER Target
+    Rust target triple.  Defaults to x86_64-pc-windows-msvc.
+    Use aarch64-pc-windows-msvc for ARM64.
+
+.EXAMPLE
+    pwsh scripts/build-boringtun-win.ps1
+    pwsh scripts/build-boringtun-win.ps1 -Target aarch64-pc-windows-msvc
+
+.NOTES
+    Prerequisites:
+        - Rust toolchain (https://rustup.rs) with the target installed:
+              rustup target add x86_64-pc-windows-msvc
+        - Visual Studio Build Tools 2019+ (for link.exe / lib.exe)
+        - Git
+#>
+
+param(
+    [string]$Target = "x86_64-pc-windows-msvc"
+)
+
+Set-StrictMode -Version Latest
+$ErrorActionPreference = "Stop"
+
+$Root      = Split-Path -Parent (Split-Path -Parent $PSCommandPath)
+$DepsDir   = Join-Path $Root "deps\boringtun"
+$CloneDir  = Join-Path $Root "build\boringtun-src"
+$RepoURL   = "https://github.com/cloudflare/boringtun.git"
+
+function Info($msg)  { Write-Host "  $msg"        -ForegroundColor Cyan  }
+function Ok($msg)    { Write-Host "  OK: $msg"    -ForegroundColor Green }
+function Fail($msg)  { Write-Host "  FAIL: $msg"  -ForegroundColor Red; exit 1 }
+
+# Validate prerequisites
+
+Info "Checking prerequisites..."
+
+if (-not (Get-Command cargo -ErrorAction SilentlyContinue)) {
+    Fail "cargo not found. Install Rust from https://rustup.rs"
+}
+if (-not (Get-Command git -ErrorAction SilentlyContinue)) {
+    Fail "git not found. Install Git from https://git-scm.com"
+}
+
+$installed = rustup target list --installed 2>&1
+if ($installed -notmatch [regex]::Escape($Target)) {
+    Info "Installing Rust target $Target..."
+    rustup target add $Target
+}
+Ok "Prerequisites satisfied"
+
+# Clone / update boringtun
+
+if (-not (Test-Path $CloneDir)) {
+    Info "Cloning boringtun..."
+    git clone --depth 1 $RepoURL $CloneDir
+} else {
+    Info "Updating boringtun..."
+    Push-Location $CloneDir
+    git pull --ff-only
+    Pop-Location
+}
+Ok "Source ready at $CloneDir"
+
+# Build
+
+Info "Building boringtun (--release, target=$Target)..."
+Push-Location $CloneDir
+cargo build --release --target $Target --features ffi-bindings 2>&1 | Write-Host
+if ($LASTEXITCODE -ne 0) { Fail "cargo build failed" }
+Pop-Location
+Ok "Build complete"
+
+# Copy artifacts
+
+New-Item -ItemType Directory -Force -Path $DepsDir | Out-Null
+
+$LibSrc = Join-Path $CloneDir "target\$Target\release\boringtun.lib"
+if (-not (Test-Path $LibSrc)) {
+    $LibSrc = Join-Path $CloneDir "target\$Target\release\boringtun_cli.lib"
+}
+if (-not (Test-Path $LibSrc)) {
+    Fail "Could not find boringtun.lib in $CloneDir\target\$Target\release\"
+}
+Copy-Item $LibSrc (Join-Path $DepsDir "boringtun.lib") -Force
+Ok "Copied boringtun.lib"
+
+$HdrSrc = Join-Path $CloneDir "boringtun\src\ffi\wireguard_ffi.h"
+if (Test-Path $HdrSrc) {
+    Copy-Item $HdrSrc (Join-Path $DepsDir "wireguard_ffi.h") -Force
+    Ok "Copied wireguard_ffi.h"
+}
+
+Write-Host ""
+Write-Host "  Build successful.  Output in:" -ForegroundColor Green
+Write-Host "    $DepsDir" -ForegroundColor White
+Write-Host ""
+Write-Host "  Next steps:" -ForegroundColor Yellow
+Write-Host "    1. Place wintun.dll (x64) next to your Artemis executable" -ForegroundColor White
+Write-Host "       Download from https://www.wintun.net" -ForegroundColor White
+Write-Host "    2. cmake -B build -DCMAKE_BUILD_TYPE=Release" -ForegroundColor White
+Write-Host "    3. cmake --build build --config Release" -ForegroundColor White