diff --git a/bitbake/lib/bb/data_smart.py b/bitbake/lib/bb/data_smart.py
index 77a3fd602f..360068fd0a 100644
--- a/bitbake/lib/bb/data_smart.py
+++ b/bitbake/lib/bb/data_smart.py
@@ -636,6 +636,7 @@ class DataSmart(MutableMapping):
                 nextnew.update(vardata.contains.keys())
             new = nextnew
         self.overrides = None
+        self.expand_cache = {}
 
     def _setvar_update_overrides(self, var, **loginfo):
         # aka pay the cookie monster