diff --git a/install.ps1 b/install.ps1
index 60df83477..f455c983d 100644
--- a/install.ps1
+++ b/install.ps1
@@ -1,4 +1,4 @@
-# install.ps1 — One-line installer for codebase-memory-mcp (Windows).
+# install.ps1 - One-line installer for codebase-memory-mcp (Windows).
 #
 # Usage: see README.md for install instructions.
 #
@@ -103,7 +103,7 @@ foreach ($arg in $args) {
 # PROCESSOR_ARCHITEW6432, which is unset for 64-bit emulated processes. Fall back
 # to the env vars only if the .NET API is somehow unavailable.
 if ($env:CBM_ARCH) {
-    # Explicit override wins — used by CI/tests, and an escape hatch under x64
+    # Explicit override wins - used by CI/tests, and an escape hatch under x64
     # emulation on ARM64 where no in-process detection is reliable.
     $Arch = $env:CBM_ARCH
 } else {
@@ -279,7 +279,7 @@ if (Test-Path -LiteralPath $Dest -PathType Leaf) {
         catch { Start-Sleep -Milliseconds 500 }
     }
     if (-not $renamed) {
-        Write-Host "error: could not retire the existing $BinName — close all running" -ForegroundColor Red
+        Write-Host "error: could not retire the existing $BinName - close all running" -ForegroundColor Red
         Write-Host "       codebase-memory-mcp sessions and coding agents, then re-run." -ForegroundColor Red
         Remove-Item -Recurse -Force $TmpDir -ErrorAction SilentlyContinue
         exit 1
diff --git a/tests/test_windows_bundle_contract.sh b/tests/test_windows_bundle_contract.sh
index 780c13027..532462d1b 100644
--- a/tests/test_windows_bundle_contract.sh
+++ b/tests/test_windows_bundle_contract.sh
@@ -164,6 +164,19 @@ for archive, call, ui in (
 # "<dest>.retired-<timestamp>", then installs over the freed name. Without the
 # retire step every Windows update fails on a locked destination.
 installer = read("install.ps1")
+# Windows PowerShell 5.1 decodes a BOM-less .ps1 as ANSI, so a UTF-8 em-dash
+# arrives as three cp1252 characters ending in a double quote. Inside a string
+# literal that quote closes it early and the whole script dies with a cascade of
+# parse errors before its first statement runs. A BOM would fix the file on disk
+# but corrupt the documented `irm ... | iex` path, which pipes the bytes
+# straight into the parser -- so the shipped installer stays pure ASCII.
+non_ascii = sorted({ch for ch in installer if ord(ch) > 0x7F})
+require(
+    not non_ascii,
+    "install.ps1 must be pure ASCII (found: "
+    + ", ".join(f"U+{ord(ch):04X}" for ch in non_ascii)
+    + ")",
+)
 require(
     "$Dest = Join-Path $InstallDir $BinName" in installer,
     "install.ps1 must resolve the canonical install destination as $Dest",