diff --git a/install.ps1 b/install.ps1
index e598f23..5327613 100644
--- a/install.ps1
+++ b/install.ps1
@@ -39,11 +39,11 @@ if ($env:CAPA_PRINT_QUIET -eq "1") {
 }
 
 # Colors
-$ColorReset = "`e[0m"
-$ColorRed = "`e[31m"
-$ColorGreen = "`e[32m"
-$ColorYellow = "`e[33m"
-$ColorBlue = "`e[34m"
+$ColorReset = "$([char]27)[0m"
+$ColorRed = "$([char]27)[31m"
+$ColorGreen = "$([char]27)[32m"
+$ColorYellow = "$([char]27)[33m"
+$ColorBlue = "$([char]27)[34m"
 
 function Show-Usage {
     Write-Host @"
@@ -108,7 +108,7 @@ function Write-Info {
 function Write-Success {
     param([string]$Message)
     if (-not $Quiet) {
-        Write-Host "${ColorGreen}✓${ColorReset} $Message"
+        Write-Host "${ColorGreen}OK${ColorReset} $Message"
     }
 }
 
@@ -250,9 +250,9 @@ function Install-Capa {
     $bannerPad = [Math]::Max(1, $bannerInner - $bannerTitle.Length)
     $bannerSpaces = " " * $bannerPad
     Write-Host ""
-    Write-Host "${ColorGreen}╔═══════════════════════════════════════╗${ColorReset}"
-    Write-Host "${ColorGreen}║${bannerTitle}${bannerSpaces}║${ColorReset}"
-    Write-Host "${ColorGreen}╚═══════════════════════════════════════╝${ColorReset}"
+    Write-Host "${ColorGreen}+---------------------------------------+${ColorReset}"
+    Write-Host "${ColorGreen}|${bannerTitle}${bannerSpaces}|${ColorReset}"
+    Write-Host "${ColorGreen}+---------------------------------------+${ColorReset}"
     Write-Host ""
     
     # Detect architecture
@@ -321,13 +321,13 @@ function Install-Capa {
     # Replace existing binary (fixes #19). On Windows a running .exe is locked
     # and cannot be overwritten, but it *can* be renamed within the same
     # directory while it runs (the OS keeps the file handle regardless of name).
-    # So move the old binary aside first — that frees $destPath — then drop the
+    # So move the old binary aside first (that frees $destPath), then drop the
     # new binary in. This makes the upgrade succeed even if the previous capa
     # process hasn't fully exited yet, instead of relying on a timing race.
     $backupPath = "$destPath.old"
     if (Test-Path $destPath) {
         # Remove any leftover backup from a prior upgrade (best-effort; harmless
-        # if it's still locked — it'll be cleaned on the next run).
+        # if it's still locked; it'll be cleaned on the next run).
         if (Test-Path $backupPath) {
             Remove-Item -LiteralPath $backupPath -Force -ErrorAction SilentlyContinue
         }
@@ -375,7 +375,7 @@ function Install-Capa {
     }
 
     # New binary is in place; clean up the old one. This will fail silently if
-    # the previous capa process is still running (the file stays locked) — the
+    # the previous capa process is still running (the file stays locked); the
     # leftover .old is then removed by the next upgrade.
     if (Test-Path $backupPath) {
         Remove-Item -LiteralPath $backupPath -Force -ErrorAction SilentlyContinue
@@ -388,9 +388,9 @@ function Install-Capa {
     
     # Print success message
     Write-Host ""
-    Write-Host "${ColorGreen}╔═══════════════════════════════════════╗${ColorReset}"
-    Write-Host "${ColorGreen}║  CAPA installed successfully! 🎉      ║${ColorReset}"
-    Write-Host "${ColorGreen}╚═══════════════════════════════════════╝${ColorReset}"
+    Write-Host "${ColorGreen}+---------------------------------------+${ColorReset}"
+    Write-Host "${ColorGreen}|  CAPA installed successfully!         |${ColorReset}"
+    Write-Host "${ColorGreen}+---------------------------------------+${ColorReset}"
     Write-Host ""
     Write-Host "To get started, run:"
     Write-Host "  ${ColorBlue}capa init${ColorReset}     # Initialize a new project"
diff --git a/src/cli/commands/__tests__/upgrade-plan.test.ts b/src/cli/commands/__tests__/upgrade-plan.test.ts
index ea81333..c2b69c4 100644
--- a/src/cli/commands/__tests__/upgrade-plan.test.ts
+++ b/src/cli/commands/__tests__/upgrade-plan.test.ts
@@ -1,5 +1,7 @@
 import { describe, it, expect } from 'bun:test';
 import { createHash } from 'crypto';
+import { readFileSync } from 'fs';
+import { join } from 'path';
 import {
   assertSha256Match,
   formatUpgradePreview,
@@ -131,4 +133,11 @@ describe('capa upgrade planning', () => {
     const map = parseSha256Sums(`${digest}  install.sh\n`);
     expect(map.get('install.sh')).toBe(digest);
   });
+
+  // `capa upgrade` runs install.ps1 via Windows PowerShell 5.1, which reads a
+  // BOM-less file as Windows-1252; any non-ASCII byte can break parsing.
+  it('keeps install.ps1 ASCII-only so Windows PowerShell 5.1 can parse it', () => {
+    const bytes = readFileSync(join(import.meta.dir, '../../../../install.ps1'));
+    expect(bytes.findIndex((b) => b > 0x7f)).toBe(-1);
+  });
 });
diff --git a/src/cli/commands/upgrade.ts b/src/cli/commands/upgrade.ts
index 23a719a..280056d 100644
--- a/src/cli/commands/upgrade.ts
+++ b/src/cli/commands/upgrade.ts
@@ -5,7 +5,6 @@ import { getServerStatus, stopServer } from '../utils/server-manager';
 import {
   header,
   footer,
-  success,
   info,
   error,
   isYes,
@@ -89,35 +88,14 @@ export async function upgradeCommand(): Promise<void> {
     CAPA_VERSION: plan.version,
   };
 
-  if (process.platform === 'win32') {
-    const proc = Bun.spawn(
-      [
-        'powershell.exe',
-        '-NoProfile',
-        '-ExecutionPolicy',
-        'Bypass',
-        '-File',
-        installerPath,
-      ],
-      {
-        stdout: 'ignore',
-        stderr: 'ignore',
-        stdin: 'ignore',
-        detached: true,
-        env,
-      },
-    );
-    proc.unref();
-    success(
-      'Verified installer started. This window will close; capa will update in the background.',
-    );
-    info(
-      'Restart your terminal when the installer finishes, then run `capa --version` to confirm.',
-    );
-    process.exit(0);
-  }
-
-  const proc = Bun.spawn(['bash', installerPath], {
+  // Run the installer in the foreground on every platform so failures are
+  // visible. On Windows the installer renames this running capa.exe aside
+  // before dropping the new one in, so it doesn't need us to exit first.
+  const cmd =
+    process.platform === 'win32'
+      ? ['powershell.exe', '-NoProfile', '-ExecutionPolicy', 'Bypass', '-File', installerPath]
+      : ['bash', installerPath];
+  const proc = Bun.spawn(cmd, {
     stdout: 'inherit',
     stderr: 'inherit',
     stdin: 'inherit',