diff --git a/python/MDSplus/tree.py b/python/MDSplus/tree.py
index 79cd9892d3..a8a33fca96 100644
--- a/python/MDSplus/tree.py
+++ b/python/MDSplus/tree.py
@@ -574,7 +574,7 @@ def __enter__(self):
         return self
 
     def __del__(self):
-        if not self.public:
+        if not self.public and _TreeShr is not None:
             self.__exit__()
             _TreeShr.TreeFreeDbid(self._ctx)