diff --git a/scripts/build_rayforge_windows_checkpoint.ps1 b/scripts/build_rayforge_windows_checkpoint.ps1
index ba8d1b8..724ac80 100644
--- a/scripts/build_rayforge_windows_checkpoint.ps1
+++ b/scripts/build_rayforge_windows_checkpoint.ps1
@@ -79,6 +79,12 @@ if ($PSCmdlet.ShouldProcess($addonDestination, "Stage no-device addon")) {
     New-Item -ItemType Directory -Force -Path $addonDestination | Out-Null
     Copy-Item -Path (Join-Path $addonSource "*") `
         -Destination $addonDestination -Recurse -Force
+    Get-ChildItem -LiteralPath $addonDestination -Recurse -Directory -Force |
+        Where-Object { $_.Name -eq "__pycache__" } |
+        Remove-Item -Recurse -Force
+    Get-ChildItem -LiteralPath $addonDestination -Recurse -File -Force |
+        Where-Object { $_.Extension -eq ".pyc" } |
+        Remove-Item -Force
 }
 
 $prepareArguments = @{
@@ -86,9 +92,20 @@ $prepareArguments = @{
     BuildWindowsBundle = $true
     AllowStagedPirateRayAddon = $true
 }
-& (Join-Path $PSScriptRoot "prepare_rayforge_build.ps1") @prepareArguments
-if ($LASTEXITCODE -ne 0) {
-    throw "Pinned Rayforge Windows bundle build failed"
+$pyInstallerSiteCustomize = Join-Path $PSScriptRoot "pyinstaller-sitecustomize"
+$previousPythonPath = $env:PYTHONPATH
+try {
+    $env:PYTHONPATH = if ($previousPythonPath) {
+        "$pyInstallerSiteCustomize;$previousPythonPath"
+    } else {
+        $pyInstallerSiteCustomize
+    }
+    & (Join-Path $PSScriptRoot "prepare_rayforge_build.ps1") @prepareArguments
+    if ($LASTEXITCODE -ne 0) {
+        throw "Pinned Rayforge Windows bundle build failed"
+    }
+} finally {
+    $env:PYTHONPATH = $previousPythonPath
 }
 
 $bundleName = "rayforge-vpirateray-$shortCommit"
@@ -132,6 +149,10 @@ if ($PSCmdlet.ShouldProcess($archive, "Create portable checkpoint archive")) {
 }
 
 $addonFiles = Get-ChildItem -LiteralPath $addonSource -Recurse -File |
+    Where-Object {
+        $_.Extension -ne ".pyc" -and
+        $_.FullName -notmatch '[\\/]__pycache__[\\/]'
+    } |
     Sort-Object FullName |
     ForEach-Object {
         [ordered]@{
diff --git a/scripts/pyinstaller-sitecustomize/sitecustomize.py b/scripts/pyinstaller-sitecustomize/sitecustomize.py
new file mode 100644
index 0000000..b392b62
--- /dev/null
+++ b/scripts/pyinstaller-sitecustomize/sitecustomize.py
@@ -0,0 +1,6 @@
+"""Keep PyInstaller's isolated analysis from initializing a GTK display."""
+
+import gi
+
+
+gi.disable_legacy_autoinit()
diff --git a/tests/test_m1_acceptance_pipeline.py b/tests/test_m1_acceptance_pipeline.py
index 808d1df..a9525ee 100644
--- a/tests/test_m1_acceptance_pipeline.py
+++ b/tests/test_m1_acceptance_pipeline.py
@@ -6,6 +6,9 @@ from pathlib import Path
 ROOT = Path(__file__).resolve().parents[1]
 ACCEPTANCE = ROOT / "scripts" / "run_m1_no_device_acceptance.py"
 BUILD = ROOT / "scripts" / "build_rayforge_windows_checkpoint.ps1"
+PYINSTALLER_SITE_CUSTOMIZE = (
+    ROOT / "scripts" / "pyinstaller-sitecustomize" / "sitecustomize.py"
+)
 VERIFY = ROOT / "scripts" / "verify_rayforge_windows_checkpoint.py"
 UPSTREAM = ROOT / "upstreams" / "rayforge.json"
 
@@ -54,6 +57,14 @@ class M1AcceptancePipelineTests(unittest.TestCase):
         self.assertIn("-LiteralPath $artifactInstaller", source)
         self.assertIn("checkout must be clean", source)
         self.assertIn("Artifact root must be absent or empty", source)
+        self.assertIn('Name -eq "__pycache__"', source)
+        self.assertIn('Extension -eq ".pyc"', source)
+        self.assertIn('Extension -ne ".pyc"', source)
+        self.assertIn("pyinstaller-sitecustomize", source)
+        self.assertIn("$env:PYTHONPATH", source)
+
+        site_customize = PYINSTALLER_SITE_CUSTOMIZE.read_text(encoding="utf-8")
+        self.assertIn("gi.disable_legacy_autoinit()", site_customize)
 
     def test_acceptance_has_no_hardware_commands(self):
         source = ACCEPTANCE.read_text(encoding="utf-8").lower()