diff --git a/browser/base/content/browser.js b/browser/base/content/browser.js
index 34d2e6c0019..210684e8873 100644
--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@@ -2224,6 +2224,7 @@ function UpdateUrlbarSearchSplitterState()
       splitter.setAttribute("resizebefore", "flex");
       splitter.setAttribute("resizeafter", "flex");
       splitter.setAttribute("skipintoolbarset", "true");
+      splitter.setAttribute("nooverflow", "true");
       splitter.className = "chromeclass-toolbar-additional";
     }
     urlbar.parentNode.insertBefore(splitter, ibefore);
diff --git a/browser/components/customizableui/src/CustomizableUI.jsm b/browser/components/customizableui/src/CustomizableUI.jsm
index f3675c27843..97bf6fd9750 100644
--- a/browser/components/customizableui/src/CustomizableUI.jsm
+++ b/browser/components/customizableui/src/CustomizableUI.jsm
@@ -2328,6 +2328,9 @@ OverflowableToolbar.prototype = {
       }
       child = prevChild;
     };
+
+    let win = this._target.ownerDocument.defaultView;
+    win.UpdateUrlbarSearchSplitterState();
   },
 
   _onResize: function(aEvent) {
@@ -2353,6 +2356,9 @@ OverflowableToolbar.prototype = {
       child.classList.remove("overflowedItem");
     }
 
+    let win = this._target.ownerDocument.defaultView;
+    win.UpdateUrlbarSearchSplitterState();
+
     if (!this._collapsed.length) {
       this._toolbar.removeAttribute("overflowing");
     }