diff --git a/src/browser/base/content/ZenUIManager.mjs b/src/browser/base/content/ZenUIManager.mjs
index 9648aef8c..4cbc1dbf4 100644
--- a/src/browser/base/content/ZenUIManager.mjs
+++ b/src/browser/base/content/ZenUIManager.mjs
@@ -35,6 +35,7 @@ var gZenUIManager = {
       }
       tab.style.maxHeight = '0px';
     }
+    tabs.style.flex = '1';
     tabs.style.removeProperty('max-height');
     const toolbarRect = tabs.getBoundingClientRect();
     let height = toolbarRect.height;
@@ -44,6 +45,7 @@ var gZenUIManager = {
       }
       tab.style.removeProperty('max-height');
     }
+    tabs.style.removeProperty('flex');
     tabs.style.maxHeight = height + 'px';
   },
 
diff --git a/src/browser/base/content/zen-styles/zen-tabs/vertical-tabs.css b/src/browser/base/content/zen-styles/zen-tabs/vertical-tabs.css
index e12549cd2..f8fbda477 100644
--- a/src/browser/base/content/zen-styles/zen-tabs/vertical-tabs.css
+++ b/src/browser/base/content/zen-styles/zen-tabs/vertical-tabs.css
@@ -356,7 +356,6 @@
 #zen-browser-tabs-wrapper {
   min-height: fit-content;
   overflow-y: scroll;
-  height: 100%;
 }
 
 #vertical-pinned-tabs-container {
diff --git a/src/toolkit/content/widgets/arrowscrollbox-js.patch b/src/toolkit/content/widgets/arrowscrollbox-js.patch
index c9866a1b0..5be08cc35 100644
--- a/src/toolkit/content/widgets/arrowscrollbox-js.patch
+++ b/src/toolkit/content/widgets/arrowscrollbox-js.patch
@@ -1,13 +1,24 @@
 diff --git a/toolkit/content/widgets/arrowscrollbox.js b/toolkit/content/widgets/arrowscrollbox.js
-index 328c770d275ebbaada8a44438eaf738b1a62d985..01256a9b4510b27e180e8b11f1436621ad3e45b5 100644
+index 328c770d275ebbaada8a44438eaf738b1a62d985..c7d178295745ed975f5a3e5dea028dbeeece1704 100644
 --- a/toolkit/content/widgets/arrowscrollbox.js
 +++ b/toolkit/content/widgets/arrowscrollbox.js
-@@ -639,7 +639,7 @@
+@@ -121,8 +121,10 @@
+           );
+         });
+       });
++      if (this.id !== 'tabbrowser-arrowscrollbox') {
+       overflowObserver.observe(slot);
+       overflowObserver.observe(this.scrollbox);
++      }
+     }
+ 
+     connectedCallback() {
+@@ -639,7 +641,7 @@
  
      on_wheel(event) {
        // Don't consume the event if we can't scroll.
 -      if (!this.overflowing) {
-+      if (!this.overflowing || true) { // we handle this on ZenStartup
++      if (!this.overflowing || this.id === 'tabbrowser-arrowscrollbox') { // we handle this on ZenStartup
          return;
        }