diff --git a/src/zen/sessionstore/ZenSessionManager.sys.mjs b/src/zen/sessionstore/ZenSessionManager.sys.mjs
index 0a1ae2511..0541894d3 100644
--- a/src/zen/sessionstore/ZenSessionManager.sys.mjs
+++ b/src/zen/sessionstore/ZenSessionManager.sys.mjs
@@ -255,7 +255,7 @@ export class nsZenSessionManager {
       const windows = (state.windows || []).filter(
         (win) => !win.isPrivate && !win.isPopup && !win.isTaskbarTab && !win.isZenUnsynced
       );
-      let windowToClone = windows[0] || {};
+      let windowToClone = windows.length > 1 ? windows[windows.length - 2] : {};
       let newWindow = Cu.cloneInto(windowToClone, {});
       if (windows.length < 2) {
         // We only want to restore the sidebar object if we found
@@ -286,7 +286,7 @@ export class nsZenSessionManager {
         firstWindow: true,
       });
 
-      resolvePromise();
+      lazy.setTimeout(resolvePromise);
     });
   }
 }
diff --git a/src/zen/sessionstore/ZenWindowSync.sys.mjs b/src/zen/sessionstore/ZenWindowSync.sys.mjs
index 366067170..792478b5c 100644
--- a/src/zen/sessionstore/ZenWindowSync.sys.mjs
+++ b/src/zen/sessionstore/ZenWindowSync.sys.mjs
@@ -17,7 +17,7 @@ XPCOMUtils.defineLazyPreferenceGetter(lazy, 'gWindowSyncEnabled', 'zen.window-sy
 XPCOMUtils.defineLazyPreferenceGetter(lazy, 'gShouldLog', 'zen.window-sync.log', true);
 
 const OBSERVING = ['browser-window-before-show'];
-const INSTANT_EVENTS = ['unload'];
+const INSTANT_EVENTS = ['SSWindowClosing'];
 const EVENTS = [
   'TabOpen',
   'TabClose',
@@ -203,7 +203,7 @@ class nsZenWindowSync {
    */
   #runOnAllWindows(aWindow, aCallback) {
     for (let window of this.#browserWindows) {
-      if (window !== aWindow) {
+      if (window !== aWindow && !window._zenClosingWindow) {
         let value = aCallback(window);
         if (value) {
           return value;
@@ -224,7 +224,11 @@ class nsZenWindowSync {
 
   handleEvent(aEvent) {
     const window = aEvent.currentTarget.ownerGlobal;
-    if (!window.gZenStartup.isReady || window.gZenWorkspaces?.privateWindowOrDisabled) {
+    if (
+      !window.gZenStartup.isReady ||
+      window.gZenWorkspaces?.privateWindowOrDisabled ||
+      window._zenClosingWindow
+    ) {
       return;
     }
     if (INSTANT_EVENTS.includes(aEvent.type)) {
@@ -658,6 +662,11 @@ class nsZenWindowSync {
    */
   #onTabSwitchOrWindowFocus(aWindow, aPreviousTab = null) {
     const selectedTab = aWindow.gBrowser.selectedTab;
+    // On some occasions, such as when closing a window, this
+    // function might be called multiple times for the same tab.
+    if (selectedTab === this.#lastSelectedTab) {
+      return;
+    }
     if (aPreviousTab?._zenContentsVisible) {
       const otherTabToShow = this.#getActiveTabFromOtherWindows(
         aWindow,
@@ -853,8 +862,9 @@ class nsZenWindowSync {
     this.#onTabSwitchOrWindowFocus(aEvent.target.ownerGlobal, previousTab);
   }
 
-  on_unload(aEvent) {
+  on_SSWindowClosing(aEvent) {
     const window = aEvent.target.ownerGlobal;
+    window._zenClosingWindow = true;
     for (let eventName of EVENTS) {
       window.removeEventListener(eventName, this);
     }