diff --git a/layout/base/nsFrameTraversal.cpp b/layout/base/nsFrameTraversal.cpp
index 811485f9564b..1ca6ec81f44b 100644
--- a/layout/base/nsFrameTraversal.cpp
+++ b/layout/base/nsFrameTraversal.cpp
@@ -436,7 +436,7 @@ nsFrameIterator::GetLastChild(nsIFrame* aFrame)
     result = nsPlaceholderFrame::GetRealFrameFor(result);
     
     if (result && IsPopupFrame(result))
-      result = GetNextSibling(result);
+      result = GetPrevSibling(result);
   }
   return result;
 }