diff --git a/accessible/xul/XULTreeAccessible.cpp b/accessible/xul/XULTreeAccessible.cpp
index f87427cc734a..ee6e36f2f109 100644
--- a/accessible/xul/XULTreeAccessible.cpp
+++ b/accessible/xul/XULTreeAccessible.cpp
@@ -144,7 +144,7 @@ XULTreeAccessible::Value(nsString& aValue)
 void
 XULTreeAccessible::Shutdown()
 {
-  if (!mDoc->IsDefunct()) {
+  if (mDoc && !mDoc->IsDefunct()) {
     UnbindCacheEntriesFromDocument(mAccessibleCache);
   }
 
diff --git a/accessible/xul/XULTreeGridAccessible.cpp b/accessible/xul/XULTreeGridAccessible.cpp
index 58fd67fd8abb..08f2c60eabd3 100644
--- a/accessible/xul/XULTreeGridAccessible.cpp
+++ b/accessible/xul/XULTreeGridAccessible.cpp
@@ -277,7 +277,7 @@ NS_IMPL_RELEASE_INHERITED(XULTreeGridRowAccessible,
 void
 XULTreeGridRowAccessible::Shutdown()
 {
-  if (!mDoc->IsDefunct()) {
+  if (mDoc && !mDoc->IsDefunct()) {
     UnbindCacheEntriesFromDocument(mAccessibleCache);
   }