diff --git a/js/src/gc/GC.cpp b/js/src/gc/GC.cpp
index 3ef53358bc10..578872cd1955 100644
--- a/js/src/gc/GC.cpp
+++ b/js/src/gc/GC.cpp
@@ -2851,6 +2851,9 @@ void GCRuntime::finishCollection() {
   for (GCZonesIter zone(this); !zone.done(); zone.next()) {
     zone->changeGCState(Zone::Finished, Zone::NoGC);
     zone->notifyObservingDebuggers();
+    for (RealmsInZoneIter realm(zone); !realm.done(); realm.next()) {
+      realm->clearAllocatedDuringGC();
+    }
   }
 
 #ifdef JS_GC_ZEAL
diff --git a/js/src/vm/Realm-inl.h b/js/src/vm/Realm-inl.h
index 39b384be7178..90331aad1921 100644
--- a/js/src/vm/Realm-inl.h
+++ b/js/src/vm/Realm-inl.h
@@ -35,9 +35,14 @@ inline bool JS::Realm::hasLiveGlobal() const {
 }
 
 inline bool JS::Realm::marked() const {
-  // Preserve this Realm if it has a live global or if it has been entered (to
-  // ensure we don't destroy the Realm while we're allocating its global).
-  return hasLiveGlobal() || hasBeenEnteredIgnoringJit();
+  // The Realm survives in the following cases:
+  //  - its global is live
+  //  - it has been entered (to ensure we don't destroy the Realm while we're
+  //    allocating its global)
+  //  - it was allocated after the start of an incremental GC (as there may be
+  //    pointers to it from other GC things)
+  return hasLiveGlobal() || hasBeenEnteredIgnoringJit() ||
+         allocatedDuringIncrementalGC_;
 }
 
 /* static */ inline js::ObjectRealm& js::ObjectRealm::get(const JSObject* obj) {
diff --git a/js/src/vm/Realm.cpp b/js/src/vm/Realm.cpp
index 489219be7100..50253f512fad 100644
--- a/js/src/vm/Realm.cpp
+++ b/js/src/vm/Realm.cpp
@@ -55,6 +55,8 @@ Realm::Realm(Compartment* comp, const JS::RealmOptions& options)
       objects_(zone_),
       randomKeyGenerator_(runtime_->forkRandomKeyGenerator()),
       debuggers_(zone_),
+      allocatedDuringIncrementalGC_(zone_->isGCMarkingOrSweeping() ||
+                                    zone_->isGCFinished()),
       wasm(runtime_) {
   runtime_->numRealms++;
 }
diff --git a/js/src/vm/Realm.h b/js/src/vm/Realm.h
index 385a0a9471ab..da041a76e6f1 100644
--- a/js/src/vm/Realm.h
+++ b/js/src/vm/Realm.h
@@ -406,6 +406,7 @@ class JS::Realm : public JS::shadow::Realm {
   friend class js::AutoRestoreRealmDebugMode;
 
   bool isSystem_ = false;
+  bool allocatedDuringIncrementalGC_;
 
   js::UniquePtr<js::coverage::LCovRealm> lcovRealm_ = nullptr;
 
@@ -615,6 +616,7 @@ class JS::Realm : public JS::shadow::Realm {
   }
 
   inline bool marked() const;
+  void clearAllocatedDuringGC() { allocatedDuringIncrementalGC_ = false; }
 
   /*
    * The principals associated with this realm. Note that the same several