diff --git a/embedding/components/webbrowserpersist/src/nsWebBrowserPersist.cpp b/embedding/components/webbrowserpersist/src/nsWebBrowserPersist.cpp
index 166d4fa46b7..ba1bf784be3 100644
--- a/embedding/components/webbrowserpersist/src/nsWebBrowserPersist.cpp
+++ b/embedding/components/webbrowserpersist/src/nsWebBrowserPersist.cpp
@@ -3834,11 +3834,17 @@ nsWebBrowserPersist::MakeAndStoreLocalFilenameInURIMap(
 
     // Create a sensibly named filename for the URI and store in the URI map
     nsCStringKey key(spec.get());
+    URIData *data;
     if (mURIMap.Exists(&key))
     {
+        data = (URIData *) mURIMap.Get(&key);
+        if (aNeedsPersisting)
+        {
+          data->mNeedsPersisting = PR_TRUE;
+        }
         if (aData)
         {
-            *aData = (URIData *) mURIMap.Get(&key);
+            *aData = data;
         }
         return NS_OK;
     }
@@ -3849,7 +3855,7 @@ nsWebBrowserPersist::MakeAndStoreLocalFilenameInURIMap(
     NS_ENSURE_SUCCESS(rv, NS_ERROR_FAILURE);
 
     // Store the file name
-    URIData *data = new URIData;
+    data = new URIData;
     NS_ENSURE_TRUE(data, NS_ERROR_OUT_OF_MEMORY);
 
     data->mNeedsPersisting = aNeedsPersisting;