diff --git a/.github/workflows/build-desktop.yml b/.github/workflows/build-desktop.yml
index 11391ec..35e4310 100644
--- a/.github/workflows/build-desktop.yml
+++ b/.github/workflows/build-desktop.yml
@@ -104,7 +104,7 @@ jobs:
           python scripts/build.py --platform macos $REFRESH_ARG
 
       - name: Package dmg
-        run: hdiutil create -volname "StreamCap" -srcfolder "dist/StreamCap.app" -ov -format UDZO "dist/StreamCap-macos.dmg"
+        run: bash scripts/create_macos_dmg.sh "dist/StreamCap.app" "dist/StreamCap-macos.dmg"
 
       - name: Upload artifact
         uses: actions/upload-artifact@v4
diff --git a/scripts/create_macos_dmg.sh b/scripts/create_macos_dmg.sh
new file mode 100644
index 0000000..79683c3
--- /dev/null
+++ b/scripts/create_macos_dmg.sh
@@ -0,0 +1,83 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+APP_PATH="${1:-dist/StreamCap.app}"
+DMG_PATH="${2:-dist/StreamCap-macos.dmg}"
+VOLUME_NAME="${3:-StreamCap}"
+BACKGROUND_IMAGE="${4:-assets/images/dmg.jpg}"
+
+if [ ! -d "$APP_PATH" ]; then
+  echo "App bundle not found: $APP_PATH" >&2
+  exit 1
+fi
+
+if [ ! -f "$BACKGROUND_IMAGE" ]; then
+  echo "DMG background image not found: $BACKGROUND_IMAGE" >&2
+  exit 1
+fi
+
+WORK_DIR="$(mktemp -d)"
+MOUNT_DIR="$WORK_DIR/mount"
+RW_DMG="$WORK_DIR/$VOLUME_NAME-rw.dmg"
+DEVICE=""
+
+cleanup() {
+  if [ -n "$DEVICE" ]; then
+    hdiutil detach "$DEVICE" -quiet || true
+  fi
+  rm -rf "$WORK_DIR"
+}
+trap cleanup EXIT
+
+mkdir -p "$MOUNT_DIR"
+
+APP_SIZE_MB="$(du -sm "$APP_PATH" | awk '{print $1}')"
+DMG_SIZE_MB="$((APP_SIZE_MB + 200))"
+
+hdiutil create "$RW_DMG" \
+  -volname "$VOLUME_NAME" \
+  -size "${DMG_SIZE_MB}m" \
+  -fs HFS+ \
+  -format UDRW \
+  -quiet
+
+DEVICE="$(hdiutil attach "$RW_DMG" -readwrite -noverify -noautoopen -mountpoint "$MOUNT_DIR" | awk '/Apple_HFS/ {print $1; exit}')"
+
+cp -R "$APP_PATH" "$MOUNT_DIR/"
+ln -s /Applications "$MOUNT_DIR/Applications"
+mkdir -p "$MOUNT_DIR/.background"
+cp "$BACKGROUND_IMAGE" "$MOUNT_DIR/.background/background.jpg"
+
+osascript <<APPLESCRIPT
+tell application "Finder"
+  tell disk "$VOLUME_NAME"
+    open
+    set current view of container window to icon view
+    set toolbar visible of container window to false
+    set statusbar visible of container window to false
+    set the bounds of container window to {100, 100, 930, 580}
+    set viewOptions to the icon view options of container window
+    set arrangement of viewOptions to not arranged
+    set icon size of viewOptions to 96
+    set background picture of viewOptions to file ".background:background.jpg"
+    set position of item "StreamCap.app" of container window to {200, 250}
+    set position of item "Applications" of container window to {630, 250}
+    update without registering applications
+    delay 2
+    close
+  end tell
+end tell
+APPLESCRIPT
+
+hdiutil detach "$DEVICE" -quiet
+DEVICE=""
+
+mkdir -p "$(dirname "$DMG_PATH")"
+hdiutil convert "$RW_DMG" \
+  -format UDZO \
+  -imagekey zlib-level=9 \
+  -o "$DMG_PATH" \
+  -ov \
+  -quiet
+
+echo "Created DMG: $DMG_PATH"