diff --git a/browser/components/customizableui/src/CustomizableUI.jsm b/browser/components/customizableui/src/CustomizableUI.jsm
index 6f086d9cd162..6e0cb152e7ec 100644
--- a/browser/components/customizableui/src/CustomizableUI.jsm
+++ b/browser/components/customizableui/src/CustomizableUI.jsm
@@ -1695,7 +1695,10 @@ let CustomizableUIInternal = {
 
       // If the widget doesn't have an existing placement, and it hasn't been
       // seen before, then add it to its default area so it can be used.
-      if (autoAdd && !widget.currentArea && !gSeenWidgets.has(widget.id)) {
+      // If the widget is not removable, we *have* to add it to its default
+      // area here.
+      let canBeAutoAdded = autoAdd && !gSeenWidgets.has(widget.id);
+      if (!widget.currentArea && (!widget.removable || canBeAutoAdded)) {
         this.beginBatchUpdate();
         try {
           gSeenWidgets.add(widget.id);
diff --git a/browser/components/customizableui/test/browser.ini b/browser/components/customizableui/test/browser.ini
index 3a7dfad508bf..e80ed076dbc1 100644
--- a/browser/components/customizableui/test/browser.ini
+++ b/browser/components/customizableui/test/browser.ini
@@ -48,4 +48,5 @@ skip-if = os == "mac"
 [browser_944887_destroyWidget_should_destroy_in_palette.js]
 [browser_945739_showInPrivateBrowsing_customize_mode.js]
 [browser_947987_removable_default.js]
+[browser_948985_non_removable_defaultArea.js]
 [browser_panel_toggle.js]
diff --git a/browser/components/customizableui/test/browser_948985_non_removable_defaultArea.js b/browser/components/customizableui/test/browser_948985_non_removable_defaultArea.js
new file mode 100644
index 000000000000..456c9ed02a97
--- /dev/null
+++ b/browser/components/customizableui/test/browser_948985_non_removable_defaultArea.js
@@ -0,0 +1,32 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+const kWidgetId = "test-destroy-non-removable-defaultArea";
+
+add_task(function() {
+  let spec = {id: kWidgetId, label: "Test non-removable defaultArea re-adding.",
+              removable: false, defaultArea: CustomizableUI.AREA_NAVBAR};
+  CustomizableUI.createWidget(spec);
+  let placement = CustomizableUI.getPlacementOfWidget(kWidgetId);
+  ok(placement, "Should have placed the widget.");
+  is(placement && placement.area, CustomizableUI.AREA_NAVBAR, "Widget should be in navbar");
+  CustomizableUI.destroyWidget(kWidgetId);
+  CustomizableUI.removeWidgetFromArea(kWidgetId);
+
+  CustomizableUI.createWidget(spec);
+  ok(placement, "Should have placed the widget.");
+  is(placement && placement.area, CustomizableUI.AREA_NAVBAR, "Widget should be in navbar");
+  CustomizableUI.destroyWidget(kWidgetId);
+  CustomizableUI.removeWidgetFromArea(kWidgetId);
+
+  const kPrefCustomizationAutoAdd = "browser.uiCustomization.autoAdd";
+  Services.prefs.setBoolPref(kPrefCustomizationAutoAdd, false);
+  CustomizableUI.createWidget(spec);
+  ok(placement, "Should have placed the widget.");
+  is(placement && placement.area, CustomizableUI.AREA_NAVBAR, "Widget should be in navbar");
+  CustomizableUI.destroyWidget(kWidgetId);
+  CustomizableUI.removeWidgetFromArea(kWidgetId);
+  Services.prefs.clearUserPref(kPrefCustomizationAutoAdd);
+});
+