--- a/dom/base/nsDocument.cpp
+++ b/dom/base/nsDocument.cpp
@@ -5227,17 +5227,17 @@ nsIDocument::InsertAnonymousContent(Elem
   return anonymousContent.forget();
 }
 
 void
 nsIDocument::RemoveAnonymousContent(AnonymousContent& aContent,
                                     ErrorResult& aRv)
 {
   nsIPresShell* shell = GetShell();
-  if (!shell) {
+  if (!shell || !shell->GetCanvasFrame()) {
     aRv.Throw(NS_ERROR_UNEXPECTED);
     return;
   }
 
   nsCOMPtr<Element> container = shell->GetCanvasFrame()
                                      ->GetCustomContentContainer();
   if (!container) {
     aRv.Throw(NS_ERROR_UNEXPECTED);