diff --git a/eeschema/sch_edit_frame.cpp b/eeschema/sch_edit_frame.cpp
index 36bb651bea..34e1494af2 100644
--- a/eeschema/sch_edit_frame.cpp
+++ b/eeschema/sch_edit_frame.cpp
@@ -709,6 +709,8 @@ void SCH_EDIT_FRAME::HardRedraw()
 
     for( std::pair<const wxString, LIB_SYMBOL*>& libSymbol : screen->GetLibSymbols() )
     {
+        wxASSERT( libSymbol.second );
+
         if( libSymbol.second )
             libSymbol.second->ClearCaches();
     }