diff --git a/pcbnew/connectivity_algo.h b/pcbnew/connectivity_algo.h
index afac157cda..32d86414e4 100644
--- a/pcbnew/connectivity_algo.h
+++ b/pcbnew/connectivity_algo.h
@@ -338,7 +338,7 @@ public:
 
     const BOX2I BBox()
     {
-        if( m_dirty )
+        if( m_dirty && m_valid )
         {
             EDA_RECT box = m_parent->GetBoundingBox();
             m_bbox = BOX2I( box.GetPosition(), box.GetSize() );