diff --git a/mozilla/docshell/base/nsDocShell.cpp b/mozilla/docshell/base/nsDocShell.cpp
index b18b7a86384..fab4fbae155 100644
--- a/mozilla/docshell/base/nsDocShell.cpp
+++ b/mozilla/docshell/base/nsDocShell.cpp
@@ -3342,6 +3342,13 @@ nsDocShell::GetVisibility(PRBool * aVisibility)
         nsCOMPtr<nsIPresShell> pPresShell;
         parentDS->GetPresShell(getter_AddRefs(pPresShell));
 
+        // Null-check for crash in bug 267804
+        if (!pPresShell) {
+            NS_NOTREACHED("docshell has null pres shell");
+            *aVisibility = PR_FALSE;
+            return NS_OK;
+        }
+
         nsIContent *shellContent =
             pPresShell->GetDocument()->FindContentForSubDocument(presShell->GetDocument());
         NS_ASSERTION(shellContent, "subshell not in the map");