diff --git a/docshell/base/nsDocShell.cpp b/docshell/base/nsDocShell.cpp
index 4bbd2f72a772..c785c54daf10 100644
--- a/docshell/base/nsDocShell.cpp
+++ b/docshell/base/nsDocShell.cpp
@@ -4756,7 +4756,7 @@ nsDocShell::Destroy() {
   mCurrentURI = nullptr;
 
   if (mScriptGlobal) {
-    mScriptGlobal->DetachFromDocShell();
+    mScriptGlobal->DetachFromDocShell(!mSkipBrowsingContextDetachOnDestroy);
     mScriptGlobal = nullptr;
   }
 
diff --git a/dom/base/nsGlobalWindowInner.cpp b/dom/base/nsGlobalWindowInner.cpp
index f7e0533442dc..22a9d55281be 100644
--- a/dom/base/nsGlobalWindowInner.cpp
+++ b/dom/base/nsGlobalWindowInner.cpp
@@ -856,6 +856,7 @@ nsGlobalWindowInner::nsGlobalWindowInner(nsGlobalWindowOuter* aOuterWindow,
       mHasGamepad(false),
       mHasVREvents(false),
       mHasVRDisplayActivateEvents(false),
+      mWasCurrentInnerWindow(false),
       mHasSeenGamepadInput(false),
       mSuspendDepth(0),
       mFreezeDepth(0),
@@ -2548,19 +2549,13 @@ bool nsPIDOMWindowInner::IsCurrentInnerWindow() const {
   auto* bc = GetBrowsingContext();
   MOZ_ASSERT(bc);
 
-  nsPIDOMWindowOuter* outer;
-  // When a BC is discarded, it stops returning outer windows altogether. That
-  // doesn't work for this check, since we still want current inner window to be
-  // treated as current after that point. Simply falling back to `mOuterWindow`
-  // here isn't ideal, since it will start returning true for inner windows
-  // which were current before a remoteness switch once a BrowsingContext has
-  // been discarded, but it's not incorrect in a way which should cause
-  // significant issues.
-  if (!bc->IsDiscarded()) {
-    outer = bc->GetDOMWindow();
-  } else {
-    outer = mOuterWindow;
+  if (bc->IsDiscarded()) {
+    // If our BrowsingContext has been discarded, we consider ourselves
+    // still-current if we were current at the time it was discarded.
+    return WasCurrentInnerWindow();
   }
+
+  nsPIDOMWindowOuter* outer = bc->GetDOMWindow();
   return outer && outer->GetCurrentInnerWindow() == this;
 }
 
diff --git a/dom/base/nsGlobalWindowInner.h b/dom/base/nsGlobalWindowInner.h
index d1c9793d886e..e0c345b2271e 100644
--- a/dom/base/nsGlobalWindowInner.h
+++ b/dom/base/nsGlobalWindowInner.h
@@ -1295,9 +1295,17 @@ class nsGlobalWindowInner final : public mozilla::dom::EventTarget,
 
   // Indicates whether this window wants VRDisplayActivate events
   bool mHasVRDisplayActivateEvents : 1;
+
+  // True if this was the currently-active inner window for a BrowsingContext at
+  // the time it was discarded.
+  bool mWasCurrentInnerWindow : 1;
+  void SetWasCurrentInnerWindow() { mWasCurrentInnerWindow = true; }
+  bool WasCurrentInnerWindow() const override { return mWasCurrentInnerWindow; }
+
+  bool mHasSeenGamepadInput : 1;
+
   nsCheapSet<nsUint32HashKey> mGamepadIndexSet;
   nsRefPtrHashtable<nsUint32HashKey, mozilla::dom::Gamepad> mGamepads;
-  bool mHasSeenGamepadInput;
 
   RefPtr<nsScreen> mScreen;
 
diff --git a/dom/base/nsGlobalWindowOuter.cpp b/dom/base/nsGlobalWindowOuter.cpp
index b4ee8518a012..c0eb6867c678 100644
--- a/dom/base/nsGlobalWindowOuter.cpp
+++ b/dom/base/nsGlobalWindowOuter.cpp
@@ -2458,7 +2458,7 @@ void nsGlobalWindowOuter::SetDocShell(nsDocShell* aDocShell) {
   SetIsBackgroundInternal(!docShellActive);
 }
 
-void nsGlobalWindowOuter::DetachFromDocShell() {
+void nsGlobalWindowOuter::DetachFromDocShell(bool aIsBeingDiscarded) {
   // DetachFromDocShell means the window is being torn down. Drop our
   // reference to the script context, allowing it to be deleted
   // later. Meanwhile, keep our weak reference to the script object
@@ -2520,6 +2520,14 @@ void nsGlobalWindowOuter::DetachFromDocShell() {
     mContext = nullptr;
   }
 
+  if (aIsBeingDiscarded) {
+    // If our BrowsingContext is being discarded, make a note that our current
+    // inner window was active at the time it went away.
+    if (GetCurrentInnerWindow()) {
+      GetCurrentInnerWindowInternal()->SetWasCurrentInnerWindow();
+    }
+  }
+
   mDocShell = nullptr;
   mBrowsingContext->ClearDocShell();
 
diff --git a/dom/base/nsGlobalWindowOuter.h b/dom/base/nsGlobalWindowOuter.h
index f7b7e176d127..b3852630f740 100644
--- a/dom/base/nsGlobalWindowOuter.h
+++ b/dom/base/nsGlobalWindowOuter.h
@@ -311,7 +311,7 @@ class nsGlobalWindowOuter final : public mozilla::dom::EventTarget,
   // Outer windows only.
   bool WouldReuseInnerWindow(Document* aNewDocument);
 
-  void DetachFromDocShell();
+  void DetachFromDocShell(bool aIsBeingDiscarded);
 
   virtual nsresult SetNewDocument(
       Document* aDocument, nsISupports* aState, bool aForceReuseInnerWindow,
diff --git a/dom/base/nsPIDOMWindow.h b/dom/base/nsPIDOMWindow.h
index e6b6ef86264c..cbe61f3a007b 100644
--- a/dom/base/nsPIDOMWindow.h
+++ b/dom/base/nsPIDOMWindow.h
@@ -170,6 +170,10 @@ class nsPIDOMWindowInner : public mozIDOMWindow {
   // Returns true if this window is the same as mTopInnerWindow
   inline bool IsTopInnerWindow() const;
 
+  // Returns true if this was the current window for its BrowsingContext when it
+  // was discarded.
+  virtual bool WasCurrentInnerWindow() const = 0;
+
   // Check whether a document is currently loading (really checks if the
   // load event has completed).  May not be reset to false on errors.
   inline bool IsLoading() const;
diff --git a/dom/base/test/file_current_inner_window.html b/dom/base/test/file_current_inner_window.html
new file mode 100644
index 000000000000..8156e290005d
--- /dev/null
+++ b/dom/base/test/file_current_inner_window.html
@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8">
+  <title></title>
+  <script>
+    function isCurrentWinnerWindow() {
+      // If we are the current inner window for our BrowsingContext, bare word
+      // access to `name` will return "". If we are not, it will throw.
+      // Note that this is *not* the same as accessing `window.name`, which
+      // will go through our WindowProxy, which will always forward it to the
+      // currently-active inner window.
+      try {
+        void name;
+        return true;
+      } catch (e) {
+        return false;
+      }
+    }
+  </script>
+</head>
+<body>
+</body>
+</html>
diff --git a/dom/base/test/mochitest.ini b/dom/base/test/mochitest.ini
index d2e47507898d..13bd17211448 100644
--- a/dom/base/test/mochitest.ini
+++ b/dom/base/test/mochitest.ini
@@ -131,6 +131,7 @@ support-files =
   file_bug945152.jar
   file_bug1274806.html
   file_bug1453693.html
+  file_current_inner_window.html
   file_domwindowutils_animation.html
   file_general_document.html
   file_history_document_open.html
@@ -653,6 +654,7 @@ skip-if = verify
 [test_document_importNode_document.html]
 [test_custom_element.html]
 [test_custom_element_reflector.html]
+[test_current_inner_window.html]
 [test_domparser_null_char.html]
 [test_domparsing.html]
 [test_domrequest.html]
diff --git a/dom/base/test/test_current_inner_window.html b/dom/base/test/test_current_inner_window.html
new file mode 100644
index 000000000000..3e7a700e635c
--- /dev/null
+++ b/dom/base/test/test_current_inner_window.html
@@ -0,0 +1,61 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Test that current inner window checks are correct after navigations/discards</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<iframe id="frame"></iframe>
+
+<script type="application/javascript">
+"use strict";
+
+const TEST_FILE = "file_current_inner_window.html";
+const BASE_PATH = location.pathname.replace(/[^\/]+$/, "");
+
+let frame = document.getElementById("frame");
+
+function loadInFrame(url) {
+  return new Promise(resolve => {
+    frame.addEventListener("load", resolve, { once: true });
+    frame.contentWindow.location = url;
+  });
+}
+
+add_task(async function() {
+  await loadInFrame(TEST_FILE);
+
+  // Store the check function from the window before we navigate. After that,
+  // its bare word property accesses will continue referring to the same inner
+  // window no matter how many times the frame navigates.
+  let check1 = frame.contentWindow.isCurrentWinnerWindow;
+  ok(check1(),
+     "Initial inner window should be current before we navigate away");
+
+  await loadInFrame(`http://example.com/${BASE_PATH}/${TEST_FILE}`);
+  ok(!check1(),
+     "Initial inner window should no longer be current after we navigate away");
+  await SpecialPowers.spawn(frame, [], () => {
+    Assert.ok(this.content.wrappedJSObject.isCurrentWinnerWindow(),
+              "Remote inner window should be current after before we navigate away");
+  });
+
+  await loadInFrame(TEST_FILE);
+  ok(!check1(),
+     "Initial inner window should still not be current after we back to current process");
+  let check2 = frame.contentWindow.isCurrentWinnerWindow;
+  ok(check2(),
+     "Second in-process inner window should be current before we remove the frame");
+
+  frame.remove();
+  ok(!check1(),
+     "Initial inner window should still not be current after we remove the frame");
+  ok(check2(),
+     "Second in-process inner window should still be current after we remove the frame");
+});
+</script>
+</body>
+</html>