diff --git a/packaging/linux/package.sh b/packaging/linux/package.sh
index 9a9693aa..a9349ca4 100755
--- a/packaging/linux/package.sh
+++ b/packaging/linux/package.sh
@@ -106,6 +106,23 @@ fi
 
 # ---- AppImage -----------------------------------------------------------------------------------
 if has appimage; then
+  APPIMAGETOOL_VERSION=1.9.1
+  case "$ARCH" in
+    x86_64) APPIMAGETOOL_SHA256=ed4ce84f0d9caff66f50bcca6ff6f35aae54ce8135408b3fa33abfc3cb384eb0 ;;
+    aarch64) APPIMAGETOOL_SHA256=f0837e7448a0c1e4e650a93bb3e85802546e60654ef287576f46c71c126a9158 ;;
+    *) APPIMAGETOOL_SHA256="" ;;
+  esac
+  # appimagetool otherwise fetches the unpinned type2-runtime `continuous` build and embeds it.
+  APPIMAGE_RUNTIME_VERSION=20251108
+  case "$ARCH" in
+    x86_64) APPIMAGE_RUNTIME_SHA256=2fca8b443c92510f1483a883f60061ad09b46b978b2631c807cd873a47ec260d ;;
+    aarch64) APPIMAGE_RUNTIME_SHA256=00cbdfcf917cc6c0ff6d3347d59e0ca1f7f45a6df1a428a0d6d8a78664d87444 ;;
+    *) APPIMAGE_RUNTIME_SHA256="" ;;
+  esac
+  if [[ -z "$APPIMAGE_RUNTIME_SHA256" ]]; then
+    echo "no pinned AppImage runtime for $ARCH; build the AppImage on x86_64 or aarch64" >&2
+    exit 2
+  fi
   APPDIR="$WORK/EffectCraft.AppDir"
   cp -R "$STAGE" "$APPDIR"
   mv "$APPDIR/usr/share/doc" "$WORK/doc-unused"
@@ -116,17 +133,36 @@ if has appimage; then
 
   TOOL="${APPIMAGETOOL:-$(command -v appimagetool || true)}"
   if [[ -z "$TOOL" ]]; then
-    TOOL="$CARGO_TARGET_DIR/appimagetool-$ARCH.AppImage"
-    if [[ ! -x "$TOOL" ]]; then
-      curl --proto '=https' -fsSL -o "$TOOL" "https://github.com/AppImage/appimagetool/releases/download/continuous/appimagetool-$ARCH.AppImage"
-      chmod +x "$TOOL"
+    if [[ -z "$APPIMAGETOOL_SHA256" ]]; then
+      echo "no pinned appimagetool for $ARCH; set APPIMAGETOOL or put appimagetool on PATH" >&2
+      exit 2
     fi
+    TOOL="$CARGO_TARGET_DIR/appimagetool-$APPIMAGETOOL_VERSION-$ARCH.AppImage"
+    if [[ ! -x "$TOOL" ]]; then
+      download="$TOOL.download"
+      curl --proto '=https' -fsSL -o "$download" \
+        "https://github.com/AppImage/appimagetool/releases/download/$APPIMAGETOOL_VERSION/appimagetool-$ARCH.AppImage"
+      printf '%s  %s\n' "$APPIMAGETOOL_SHA256" "$download" | sha256sum -c -
+      chmod 755 "$download"
+      mv "$download" "$TOOL"
+    fi
+    printf '%s  %s\n' "$APPIMAGETOOL_SHA256" "$TOOL" | sha256sum -c -
   fi
+  RUNTIME="$CARGO_TARGET_DIR/appimage-runtime-$APPIMAGE_RUNTIME_VERSION-$ARCH"
+  if [[ ! -f "$RUNTIME" ]]; then
+    download="$RUNTIME.download"
+    curl --proto '=https' -fsSL -o "$download" \
+      "https://github.com/AppImage/type2-runtime/releases/download/$APPIMAGE_RUNTIME_VERSION/runtime-$ARCH"
+    printf '%s  %s\n' "$APPIMAGE_RUNTIME_SHA256" "$download" | sha256sum -c -
+    mv "$download" "$RUNTIME"
+  fi
+  printf '%s  %s\n' "$APPIMAGE_RUNTIME_SHA256" "$RUNTIME" | sha256sum -c -
   # Absolute, because appimagetool runs in $DIST below (CARGO_TARGET_DIR or APPIMAGETOOL may be
   # relative).
   OUT="$(cd "$DIST" && pwd)/$BASENAME.AppImage"
   APPDIR="$(cd "$APPDIR" && pwd)"
   TOOL="$(cd "$(dirname "$TOOL")" && pwd)/$(basename "$TOOL")"
+  RUNTIME="$(cd "$(dirname "$RUNTIME")" && pwd)/$(basename "$RUNTIME")"
   # A .zsync left by an earlier run would hide a missing zsyncmake and describe another file.
   rm -f "$OUT.zsync"
   # Update information: AppImageUpdate, AppImageLauncher and the like read it from the file and
@@ -138,7 +174,7 @@ if has appimage; then
   # Extract-and-run: works without FUSE (containers, CI). The output embeds the static runtime,
   # so users don't need libfuse2 either. With zsyncmake on the host (CI installs the zsync
   # package) appimagetool also writes the .zsync, into its working directory, hence the cd.
-  (cd "$DIST" && ARCH="$ARCH" APPIMAGE_EXTRACT_AND_RUN=1 "$TOOL" --no-appstream -u "$UPDATE_INFO" "$APPDIR" "$OUT")
+  (cd "$DIST" && ARCH="$ARCH" APPIMAGE_EXTRACT_AND_RUN=1 "$TOOL" --no-appstream --runtime-file "$RUNTIME" -u "$UPDATE_INFO" "$APPDIR" "$OUT")
   echo "wrote $OUT"
   if [[ -s "$OUT.zsync" ]]; then
     echo "wrote $OUT.zsync"
diff --git a/packaging/windows/sign.ps1 b/packaging/windows/sign.ps1
index d8f2f649..7f89586a 100644
--- a/packaging/windows/sign.ps1
+++ b/packaging/windows/sign.ps1
@@ -56,8 +56,8 @@ if (-not $haveCert -and -not $haveAzure) {
 
 $script:SignTool = Find-SignTool
 $common = @('sign', '/v', '/fd', 'SHA256', '/td', 'SHA256', '/d', 'EffectCraft', '/du', 'https://github.com/storytold/effectcraft')
-$tmp = Join-Path ([IO.Path]::GetTempPath()) "effectcraft-sign-$PID"
-New-Item -ItemType Directory -Force -Path $tmp | Out-Null
+$tmp = Join-Path ([IO.Path]::GetTempPath()) "effectcraft-sign-$([IO.Path]::GetRandomFileName())"
+New-Item -ItemType Directory -Path $tmp | Out-Null
 
 try {
   if ($haveCert) {
@@ -73,8 +73,15 @@ try {
     Write-Output "Signing with Azure Trusted Signing ($env:AZURE_SIGNING_ACCOUNT / $env:AZURE_CERT_PROFILE): $($Files -join ', ')"
     # The dlib authenticates with DefaultAzureCredential, which reads AZURE_TENANT_ID,
     # AZURE_CLIENT_ID and AZURE_CLIENT_SECRET from the environment.
+    $trustedSigningVersion = '1.0.95'
+    $trustedSigningSha256 = '3bfcf1e0a3cb42af1692f0a8ed45c15de070c2de86f28a59b2795d904d8a920f'
     $pkg = Join-Path $tmp 'trusted-signing.zip'
-    Invoke-WebRequest -Uri 'https://www.nuget.org/api/v2/package/Microsoft.Trusted.Signing.Client' -OutFile $pkg
+    $uri = "https://api.nuget.org/v3-flatcontainer/microsoft.trusted.signing.client/$trustedSigningVersion/microsoft.trusted.signing.client.$trustedSigningVersion.nupkg"
+    Invoke-WebRequest -Uri $uri -OutFile $pkg
+    $actualHash = (Get-FileHash -Path $pkg -Algorithm SHA256).Hash.ToLowerInvariant()
+    if ($actualHash -ne $trustedSigningSha256) {
+      throw "Microsoft.Trusted.Signing.Client $trustedSigningVersion checksum mismatch"
+    }
     Expand-Archive -Path $pkg -DestinationPath (Join-Path $tmp 'client') -Force
     $dlib = Get-ChildItem -Path (Join-Path $tmp 'client') -Recurse -Filter Azure.CodeSigning.Dlib.dll |
       Where-Object { $_.FullName -match '\\x64\\' } | Select-Object -First 1