diff --git a/layout/base/nsPresContext.cpp b/layout/base/nsPresContext.cpp
index 31743a9e8278..4ad726b22e61 100644
--- a/layout/base/nsPresContext.cpp
+++ b/layout/base/nsPresContext.cpp
@@ -1787,8 +1787,10 @@ nsPresContext::ThemeChangedInternal()
 
   // Recursively notify all remote leaf descendants that the
   // system theme has changed.
-  nsContentUtils::CallOnAllRemoteChildren(mDocument->GetWindow(),
-                                          NotifyThemeChanged, nullptr);
+  if (nsPIDOMWindowOuter* window = mDocument->GetWindow()) {
+    nsContentUtils::CallOnAllRemoteChildren(window,
+                                            NotifyThemeChanged, nullptr);
+  }
 }
 
 void
@@ -2118,9 +2120,11 @@ NotifyTabSizeModeChanged(TabParent* aTab, void* aArg)
 void
 nsPresContext::SizeModeChanged(nsSizeMode aSizeMode)
 {
-  nsContentUtils::CallOnAllRemoteChildren(mDocument->GetWindow(),
-                                          NotifyTabSizeModeChanged,
-                                          &aSizeMode);
+  if (nsPIDOMWindowOuter* window = mDocument->GetWindow()) {
+    nsContentUtils::CallOnAllRemoteChildren(window,
+                                            NotifyTabSizeModeChanged,
+                                            &aSizeMode);
+  }
   MediaFeatureValuesChangedAllDocuments({ MediaFeatureChangeReason::SizeModeChange });
 }