diff --git a/lib/liveWallpaper.js b/lib/liveWallpaper.js
index 342cf4d..36cf6e5 100644
--- a/lib/liveWallpaper.js
+++ b/lib/liveWallpaper.js
@@ -7,6 +7,8 @@ import * as Main from 'resource:///org/gnome/shell/ui/main.js';
 import {SettingsKey} from './settingsKeys.js';
 import {loadGstreamerModules, GSTREAMER_INSTALL_HINT} from './gstreamerAvailability.js';
 
+Gio._promisify(Gio.DBusProxy, 'new_for_bus', 'new_for_bus_finish');
+
 /**
  * Ways to get a decoded frame onto an actor, tried in order and "pinned"
  * once one works. `new Clutter.Image()` failed with "is not a constructor"
@@ -79,6 +81,7 @@ export class LiveWallpaperManager {
         this._fullscreenChangedId = 0;
         this._upowerProxy = null;
         this._upowerSignalId = 0;
+        this._powerWatchGeneration = 0;
 
         this._frameCount = 0;
         this._pollCount = 0;
@@ -428,19 +431,33 @@ export class LiveWallpaperManager {
             this._logger.debug(`Fullscreen tracking unavailable, pause-when-fullscreen disabled (${e.message ?? e})`);
         }
 
-        try {
-            this._upowerProxy = Gio.DBusProxy.new_for_bus_sync(
-                Gio.BusType.SYSTEM, Gio.DBusProxyFlags.NONE, null,
-                'org.freedesktop.UPower', '/org/freedesktop/UPower', 'org.freedesktop.UPower', null);
-            this._upowerSignalId = this._upowerProxy.connect(
-                'g-properties-changed', () => this._checkBattery());
-            this._checkBattery();
-        } catch (e) {
-            this._logger.debug(`UPower unavailable, pause-on-battery disabled (${e.message ?? e})`);
-        }
+        // Deliberately async: the *_sync() variant blocks gnome-shell's
+        // single main thread (it *is* the compositor) until the system bus
+        // replies, which can take many seconds — or the full ~25s GDBus
+        // timeout — if upowerd is still starting up or the bus is busy,
+        // exactly the conditions right after login. That froze the entire
+        // screen (and could make the session look hung/crashed) since this
+        // runs every time live wallpaper starts, including automatically
+        // at login whenever it was left enabled.
+        const watchGeneration = ++this._powerWatchGeneration;
+        Gio.DBusProxy.new_for_bus(
+            Gio.BusType.SYSTEM, Gio.DBusProxyFlags.NONE, null,
+            'org.freedesktop.UPower', '/org/freedesktop/UPower', 'org.freedesktop.UPower', null)
+            .then(proxy => {
+                if (watchGeneration !== this._powerWatchGeneration)
+                    return; // Superseded by a _stop()/_connectPowerWatches() while this was in flight.
+                this._upowerProxy = proxy;
+                this._upowerSignalId = proxy.connect('g-properties-changed', () => this._checkBattery());
+                this._checkBattery();
+            })
+            .catch(e => {
+                this._logger.debug(`UPower unavailable, pause-on-battery disabled (${e.message ?? e})`);
+            });
     }
 
     _disconnectPowerWatches() {
+        this._powerWatchGeneration++;
+
         if (this._fullscreenChangedId) {
             global.display.disconnect(this._fullscreenChangedId);
             this._fullscreenChangedId = 0;